diff --git a/FreeSql.Tests/FreeSql.Tests.Provider.Odbc/SqlServer/SqlServerExpression/DateTimeTest.cs b/FreeSql.Tests/FreeSql.Tests.Provider.Odbc/SqlServer/SqlServerExpression/DateTimeTest.cs
index ab4708bc..bdeeab9e 100644
--- a/FreeSql.Tests/FreeSql.Tests.Provider.Odbc/SqlServer/SqlServerExpression/DateTimeTest.cs
+++ b/FreeSql.Tests/FreeSql.Tests.Provider.Odbc/SqlServer/SqlServerExpression/DateTimeTest.cs
@@ -41,6 +41,31 @@ namespace FreeSql.Tests.Odbc.SqlServerExpression
             public List<TestTypeInfo> Types { get; set; }
             public DateTime Time2 { get; set; }
         }
+
+        [Fact]
+        public void this_ToString()
+        {
+            var data = new List<object>();
+            data.Add(select.Where(a => a.CreateTime.ToString().Equals(DateTime.Now)).ToList());
+            data.Add(select.Where(a => a.Type.Time.AddYears(1).ToString().Equals(DateTime.Now)).ToList());
+            data.Add(select.Where(a => a.Type.Parent.Time2.AddYears(1).ToString().Equals(DateTime.Now)).ToList());
+
+            g.sqlserver.Insert(new Topic()).ExecuteAffrows();
+            foreach (var dt in new[] { DateTime.Parse("2020-5-6 0:1:2"), DateTime.Parse("2020-11-16 13:21:22"), })
+            {
+                Assert.Equal(dt.ToString("yyyy-MM-dd HH:mm:ss.fff"), select.First(a => dt.ToString()));
+                Assert.Equal(dt.ToString("yyyy-MM-dd HH:mm:ss"), select.First(a => dt.ToString("yyyy-MM-dd HH:mm:ss")));
+                Assert.Equal(dt.ToString("yyyy-MM-dd HH:mm"), select.First(a => dt.ToString("yyyy-MM-dd HH:mm")));
+                Assert.Equal(dt.ToString("yyyy-MM-dd HH"), select.First(a => dt.ToString("yyyy-MM-dd HH")));
+                Assert.Equal(dt.ToString("yyyy-MM-dd"), select.First(a => dt.ToString("yyyy-MM-dd")));
+                Assert.Equal(dt.ToString("yyyy-MM"), select.First(a => dt.ToString("yyyy-MM")));
+                Assert.Equal(dt.ToString("yyyyMMdd"), select.First(a => dt.ToString("yyyyMMdd")));
+                Assert.Equal(dt.ToString("yyyyMM"), select.First(a => dt.ToString("yyyyMM")));
+                Assert.Equal(dt.ToString("yyyy"), select.First(a => dt.ToString("yyyy")));
+                Assert.Equal(dt.ToString("HH:mm:ss"), select.First(a => dt.ToString("HH:mm:ss")));
+                Assert.Equal(dt.ToString("yyyy MM dd HH mm ss yy M d H hh h m s tt t").Replace("上午", "AM").Replace("下午", "PM").Replace("上", "A").Replace("下", "P"), select.First(a => dt.ToString("yyyy MM dd HH mm ss yy M d H hh h m s tt t")));
+            }
+        }
         [Fact]
         public void Now()
         {
@@ -269,14 +294,6 @@ namespace FreeSql.Tests.Odbc.SqlServerExpression
             data.Add(select.Where(a => a.Type.Time.AddYears(1).Equals(DateTime.Now)).ToList());
             data.Add(select.Where(a => a.Type.Parent.Time2.AddYears(1).Equals(DateTime.Now)).ToList());
         }
-        [Fact]
-        public void this_ToString()
-        {
-            var data = new List<object>();
-            data.Add(select.Where(a => a.CreateTime.ToString().Equals(DateTime.Now)).ToList());
-            data.Add(select.Where(a => a.Type.Time.AddYears(1).ToString().Equals(DateTime.Now)).ToList());
-            data.Add(select.Where(a => a.Type.Parent.Time2.AddYears(1).ToString().Equals(DateTime.Now)).ToList());
-        }
 
         [Fact]
         public void DateTime_Compare()
diff --git a/FreeSql.Tests/FreeSql.Tests/SqlServer/SqlServerExpression/DateTimeTest.cs b/FreeSql.Tests/FreeSql.Tests/SqlServer/SqlServerExpression/DateTimeTest.cs
index aafaf6a9..284cdaf3 100644
--- a/FreeSql.Tests/FreeSql.Tests/SqlServer/SqlServerExpression/DateTimeTest.cs
+++ b/FreeSql.Tests/FreeSql.Tests/SqlServer/SqlServerExpression/DateTimeTest.cs
@@ -49,6 +49,31 @@ namespace FreeSql.Tests.SqlServerExpression
             public List<TestTypeInfo> Types { get; set; }
             public DateTime Time2 { get; set; }
         }
+
+        [Fact]
+        public void this_ToString()
+        {
+            var data = new List<object>();
+            data.Add(select.Where(a => a.CreateTime.ToString().Equals(DateTime.Now)).ToList());
+            data.Add(select.Where(a => a.Type.Time.AddYears(1).ToString().Equals(DateTime.Now)).ToList());
+            data.Add(select.Where(a => a.Type.Parent.Time2.AddYears(1).ToString().Equals(DateTime.Now)).ToList());
+
+            g.sqlserver.Insert(new Topic()).ExecuteAffrows();
+            foreach (var dt in new[] { DateTime.Parse("2020-5-6 0:1:2"), DateTime.Parse("2020-11-16 13:21:22"), })
+            {
+                Assert.Equal(dt.ToString("yyyy-MM-dd HH:mm:ss.fff"), select.First(a => dt.ToString()));
+                Assert.Equal(dt.ToString("yyyy-MM-dd HH:mm:ss"), select.First(a => dt.ToString("yyyy-MM-dd HH:mm:ss")));
+                Assert.Equal(dt.ToString("yyyy-MM-dd HH:mm"), select.First(a => dt.ToString("yyyy-MM-dd HH:mm")));
+                Assert.Equal(dt.ToString("yyyy-MM-dd HH"), select.First(a => dt.ToString("yyyy-MM-dd HH")));
+                Assert.Equal(dt.ToString("yyyy-MM-dd"), select.First(a => dt.ToString("yyyy-MM-dd")));
+                Assert.Equal(dt.ToString("yyyy-MM"), select.First(a => dt.ToString("yyyy-MM")));
+                Assert.Equal(dt.ToString("yyyyMMdd"), select.First(a => dt.ToString("yyyyMMdd")));
+                Assert.Equal(dt.ToString("yyyyMM"), select.First(a => dt.ToString("yyyyMM")));
+                Assert.Equal(dt.ToString("yyyy"), select.First(a => dt.ToString("yyyy")));
+                Assert.Equal(dt.ToString("HH:mm:ss"), select.First(a => dt.ToString("HH:mm:ss")));
+                Assert.Equal(dt.ToString("yyyy MM dd HH mm ss yy M d H hh h m s tt t").Replace("上午", "AM").Replace("下午", "PM").Replace("上", "A").Replace("下", "P"), select.First(a => dt.ToString("yyyy MM dd HH mm ss yy M d H hh h m s tt t")));
+            }
+        }
         [Fact]
         public void Now()
         {
@@ -277,14 +302,6 @@ namespace FreeSql.Tests.SqlServerExpression
             data.Add(select.Where(a => a.Type.Time.AddYears(1).Equals(DateTime.Now)).ToList());
             data.Add(select.Where(a => a.Type.Parent.Time2.AddYears(1).Equals(DateTime.Now)).ToList());
         }
-        [Fact]
-        public void this_ToString()
-        {
-            var data = new List<object>();
-            data.Add(select.Where(a => a.CreateTime.ToString().Equals(DateTime.Now)).ToList());
-            data.Add(select.Where(a => a.Type.Time.AddYears(1).ToString().Equals(DateTime.Now)).ToList());
-            data.Add(select.Where(a => a.Type.Parent.Time2.AddYears(1).ToString().Equals(DateTime.Now)).ToList());
-        }
 
         [Fact]
         public void DateTime_Compare()
diff --git a/Providers/FreeSql.Provider.Odbc/SqlServer/OdbcSqlServerExpression.cs b/Providers/FreeSql.Provider.Odbc/SqlServer/OdbcSqlServerExpression.cs
index 280a6181..d8f7dc9b 100644
--- a/Providers/FreeSql.Provider.Odbc/SqlServer/OdbcSqlServerExpression.cs
+++ b/Providers/FreeSql.Provider.Odbc/SqlServer/OdbcSqlServerExpression.cs
@@ -1,11 +1,10 @@
 锘縰sing FreeSql.Internal;
-using FreeSql.Internal.Model;
 using System;
 using System.Collections;
-using System.Collections.Generic;
 using System.Linq;
 using System.Linq.Expressions;
 using System.Text;
+using System.Text.RegularExpressions;
 
 namespace FreeSql.Odbc.SqlServer
 {
@@ -374,7 +373,49 @@ namespace FreeSql.Odbc.SqlServer
                         break;
                     case "Equals": return $"({left} = {args1})";
                     case "CompareTo": return $"datediff(second,{args1},{left})";
-                    case "ToString": return exp.Arguments.Count == 0 ? $"convert(varchar, {left}, 121)" : null;
+                    case "ToString":
+                        if (exp.Arguments.Count == 0) return $"convert(varchar, cast({left} as datetime), 121)";
+                        left = $"cast({left} as datetime)";
+                        switch (args1.TrimStart('N'))
+                        {
+                            case "'yyyy-MM-dd HH:mm:ss'": return $"convert(char(19), {left}, 120)";
+                            case "'yyyy-MM-dd HH:mm'": return $"substring(convert(char(19), {left}, 120), 1, 16)";
+                            case "'yyyy-MM-dd HH'": return $"substring(convert(char(19), {left}, 120), 1, 13)";
+                            case "'yyyy-MM-dd'": return $"convert(char(10), {left}, 23)";
+                            case "'yyyy-MM'": return $"substring(convert(char(10), {left}, 23), 1, 7)";
+                            case "'yyyyMMdd'": return $"convert(char(8), {left}, 112)";
+                            case "'yyyyMM'": return $"substring(convert(char(8), {left}, 112), 1, 6)";
+                            case "'yyyy'": return $"substring(convert(char(8), {left}, 112), 1, 4)";
+                            case "'HH:mm:ss'": return $"convert(char(8), {left}, 24)";
+                        }
+                        var nchar = args1.StartsWith("N'") ? "N" : "";
+                        return Regex.Replace(args1, "(yyyy|yy|MM|M|dd|d|HH|H|hh|h|mm|m|ss|s|tt|t)", m =>
+                        {
+                            switch (m.Groups[1].Value)
+                            {
+                                case "yyyy": return $"' + substring(convert(char(8), {left}, 112), 1, 4) + {nchar}'";
+                                case "yy": return $"' + substring(convert(char(6), {left}, 12), 1, 2) + {nchar}'";
+                                case "MM": return $"' + substring(convert(char(6), {left}, 12), 3, 2) + {nchar}'";
+                                case "M": return $"' + case when substring(convert(char(6), {left}, 12), 3, 1) = '0' then substring(convert(char(6), {left}, 12), 4, 1) else substring(convert(char(6), {left}, 12), 3, 2) end + {nchar}'";
+                                case "dd": return $"' + substring(convert(char(6), {left}, 12), 5, 2) + {nchar}'";
+                                case "d": return $"' + case when substring(convert(char(6), {left}, 12), 5, 1) = '0' then substring(convert(char(6), {left}, 12), 6, 1) else substring(convert(char(6), {left}, 12), 5, 2) end + {nchar}'";
+                                case "HH": return $"' + substring(convert(char(8), {left}, 24), 1, 2) + {nchar}'";
+                                case "H": return $"' + case when substring(convert(char(8), {left}, 24), 1, 1) = '0' then substring(convert(char(8), {left}, 24), 2, 1) else substring(convert(char(8), {left}, 24), 1, 2) end + {nchar}'";
+                                case "hh":
+                                    return $"' + case cast(case when substring(convert(char(8), {left}, 24), 1, 1) = '0' then substring(convert(char(8), {left}, 24), 2, 1) else substring(convert(char(8), {left}, 24), 1, 2) end as int) % 12" +
+                             $"when 0 then '12' when 1 then '01' when 2 then '02' when 3 then '03' when 4 then '04' when 5 then '05' when 6 then '06' when 7 then '07' when 8 then '08' when 9 then '09' when 10 then '10' when 11 then '11' end + {nchar}'";
+                                case "h":
+                                    return $"' + case cast(case when substring(convert(char(8), {left}, 24), 1, 1) = '0' then substring(convert(char(8), {left}, 24), 2, 1) else substring(convert(char(8), {left}, 24), 1, 2) end as int) % 12" +
+                              $"when 0 then '12' when 1 then '1' when 2 then '2' when 3 then '3' when 4 then '4' when 5 then '5' when 6 then '6' when 7 then '7' when 8 then '8' when 9 then '9' when 10 then '10' when 11 then '11' end + {nchar}'";
+                                case "mm": return $"' + substring(convert(char(8), {left}, 24), 4, 2) + {nchar}'";
+                                case "m": return $"' + case when substring(convert(char(8), {left}, 24), 4, 1) = '0' then substring(convert(char(8), {left}, 24), 5, 1) else substring(convert(char(8), {left}, 24), 4, 2) end + {nchar}'";
+                                case "ss": return $"' + substring(convert(char(8), {left}, 24), 7, 2) + {nchar}'";
+                                case "s": return $"' + case when substring(convert(char(8), {left}, 24), 7, 1) = '0' then substring(convert(char(8), {left}, 24), 8, 1) else substring(convert(char(8), {left}, 24), 7, 2) end + {nchar}'";
+                                case "tt": return $"' + case when cast(case when substring(convert(char(8), {left}, 24), 1, 1) = '0' then substring(convert(char(8), {left}, 24), 2, 1) else substring(convert(char(8), {left}, 24), 1, 2) end as int) >= 12 then 'PM' else 'AM' end + {nchar}'";
+                                case "t": return $"' + case when cast(case when substring(convert(char(8), {left}, 24), 1, 1) = '0' then substring(convert(char(8), {left}, 24), 2, 1) else substring(convert(char(8), {left}, 24), 1, 2) end as int) >= 12 then 'P' else 'A' end + {nchar}'";
+                            }
+                            return m.Groups[0].Value;
+                        });
                 }
             }
             return null;
diff --git a/Providers/FreeSql.Provider.SqlServer/SqlServerExpression.cs b/Providers/FreeSql.Provider.SqlServer/SqlServerExpression.cs
index 4abd09ac..b4b7c563 100644
--- a/Providers/FreeSql.Provider.SqlServer/SqlServerExpression.cs
+++ b/Providers/FreeSql.Provider.SqlServer/SqlServerExpression.cs
@@ -1,11 +1,10 @@
 锘縰sing FreeSql.Internal;
-using FreeSql.Internal.Model;
 using System;
 using System.Collections;
-using System.Collections.Generic;
 using System.Linq;
 using System.Linq.Expressions;
 using System.Text;
+using System.Text.RegularExpressions;
 
 namespace FreeSql.SqlServer
 {
@@ -374,7 +373,47 @@ namespace FreeSql.SqlServer
                         break;
                     case "Equals": return $"({left} = {args1})";
                     case "CompareTo": return $"datediff(second,{args1},{left})";
-                    case "ToString": return exp.Arguments.Count == 0 ? $"convert(varchar, {left}, 121)" : null;
+                    case "ToString":
+                        if (exp.Arguments.Count == 0) return $"convert(varchar, cast({left} as datetime), 121)";
+                        left = $"cast({left} as datetime)";
+                        switch (args1.TrimStart('N'))
+                        {
+                            case "'yyyy-MM-dd HH:mm:ss'": return $"convert(char(19), {left}, 120)";
+                            case "'yyyy-MM-dd HH:mm'": return $"substring(convert(char(19), {left}, 120), 1, 16)";
+                            case "'yyyy-MM-dd HH'": return $"substring(convert(char(19), {left}, 120), 1, 13)";
+                            case "'yyyy-MM-dd'": return $"convert(char(10), {left}, 23)";
+                            case "'yyyy-MM'": return $"substring(convert(char(10), {left}, 23), 1, 7)";
+                            case "'yyyyMMdd'": return $"convert(char(8), {left}, 112)";
+                            case "'yyyyMM'": return $"substring(convert(char(8), {left}, 112), 1, 6)";
+                            case "'yyyy'": return $"substring(convert(char(8), {left}, 112), 1, 4)";
+                            case "'HH:mm:ss'": return $"convert(char(8), {left}, 24)";
+                        }
+                        var nchar = args1.StartsWith("N'") ? "N" : "";
+                        return Regex.Replace(args1, "(yyyy|yy|MM|M|dd|d|HH|H|hh|h|mm|m|ss|s|tt|t)", m =>
+                        {
+                            switch (m.Groups[1].Value)
+                            {
+                                case "yyyy": return $"' + substring(convert(char(8), {left}, 112), 1, 4) + {nchar}'";
+                                case "yy": return $"' + substring(convert(char(6), {left}, 12), 1, 2) + {nchar}'";
+                                case "MM": return $"' + substring(convert(char(6), {left}, 12), 3, 2) + {nchar}'";
+                                case "M": return $"' + case when substring(convert(char(6), {left}, 12), 3, 1) = '0' then substring(convert(char(6), {left}, 12), 4, 1) else substring(convert(char(6), {left}, 12), 3, 2) end + {nchar}'";
+                                case "dd": return $"' + substring(convert(char(6), {left}, 12), 5, 2) + {nchar}'";
+                                case "d": return $"' + case when substring(convert(char(6), {left}, 12), 5, 1) = '0' then substring(convert(char(6), {left}, 12), 6, 1) else substring(convert(char(6), {left}, 12), 5, 2) end + {nchar}'";
+                                case "HH": return $"' + substring(convert(char(8), {left}, 24), 1, 2) + {nchar}'";
+                                case "H": return $"' + case when substring(convert(char(8), {left}, 24), 1, 1) = '0' then substring(convert(char(8), {left}, 24), 2, 1) else substring(convert(char(8), {left}, 24), 1, 2) end + {nchar}'";
+                                case "hh": return $"' + case cast(case when substring(convert(char(8), {left}, 24), 1, 1) = '0' then substring(convert(char(8), {left}, 24), 2, 1) else substring(convert(char(8), {left}, 24), 1, 2) end as int) % 12" +
+                                    $"when 0 then '12' when 1 then '01' when 2 then '02' when 3 then '03' when 4 then '04' when 5 then '05' when 6 then '06' when 7 then '07' when 8 then '08' when 9 then '09' when 10 then '10' when 11 then '11' end + {nchar}'";
+                                case "h": return $"' + case cast(case when substring(convert(char(8), {left}, 24), 1, 1) = '0' then substring(convert(char(8), {left}, 24), 2, 1) else substring(convert(char(8), {left}, 24), 1, 2) end as int) % 12" +
+                                    $"when 0 then '12' when 1 then '1' when 2 then '2' when 3 then '3' when 4 then '4' when 5 then '5' when 6 then '6' when 7 then '7' when 8 then '8' when 9 then '9' when 10 then '10' when 11 then '11' end + {nchar}'";
+                                case "mm": return $"' + substring(convert(char(8), {left}, 24), 4, 2) + {nchar}'";
+                                case "m": return $"' + case when substring(convert(char(8), {left}, 24), 4, 1) = '0' then substring(convert(char(8), {left}, 24), 5, 1) else substring(convert(char(8), {left}, 24), 4, 2) end + {nchar}'";
+                                case "ss": return $"' + substring(convert(char(8), {left}, 24), 7, 2) + {nchar}'";
+                                case "s": return $"' + case when substring(convert(char(8), {left}, 24), 7, 1) = '0' then substring(convert(char(8), {left}, 24), 8, 1) else substring(convert(char(8), {left}, 24), 7, 2) end + {nchar}'";
+                                case "tt": return $"' + case when cast(case when substring(convert(char(8), {left}, 24), 1, 1) = '0' then substring(convert(char(8), {left}, 24), 2, 1) else substring(convert(char(8), {left}, 24), 1, 2) end as int) >= 12 then 'PM' else 'AM' end + {nchar}'";
+                                case "t": return $"' + case when cast(case when substring(convert(char(8), {left}, 24), 1, 1) = '0' then substring(convert(char(8), {left}, 24), 2, 1) else substring(convert(char(8), {left}, 24), 1, 2) end as int) >= 12 then 'P' else 'A' end + {nchar}'";
+                            }
+                            return m.Groups[0].Value;
+                        });
                 }
             }
             return null;