diff --git a/Src/Asp.NetCore2/SqlSeverTest/SqlSeverTest/Demos/C_ExtSqlFun.cs b/Src/Asp.NetCore2/SqlSeverTest/SqlSeverTest/Demos/C_ExtSqlFun.cs
new file mode 100644
index 000000000..f0b4c0580
--- /dev/null
+++ b/Src/Asp.NetCore2/SqlSeverTest/SqlSeverTest/Demos/C_ExtSqlFun.cs
@@ -0,0 +1,53 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using SqlSugar;
+using OrmTest.Models;
+
+namespace OrmTest.Demo
+{
+    public class ExtSqlFun : DemoBase
+    {
+        public static SqlSugarClient GetDb()
+        {
+            //Create ext method
+            var expMethods = new List<SqlFuncExternal>();
+            expMethods.Add(new SqlFuncExternal()
+            {
+                UniqueMethodName = "MyToString",
+                MethodValue = (expInfo, dbType, expContext) =>
+                {
+                    return string.Format("CAST({0} AS VARCHAR(MAX))", expInfo.Args[0].MemberName);
+                }
+            });
+
+            var config = new ConnectionConfig()
+            {
+                ConnectionString = Config.ConnectionString,
+                DbType = DbType.SqlServer,
+                IsAutoCloseConnection = true,
+                ConfigureExternalServices = new ConfigureExternalServices()
+                {
+                    SqlFuncServices = expMethods//set ext method
+                }
+            };
+
+            SqlSugarClient db = new SqlSugarClient(config);
+            return db;
+        }
+
+        public static string MyToString<T>(T str)
+        {
+            throw new NotSupportedException("Can only be used in expressions");
+        }
+
+        public static void Init()
+        {
+            var db = GetDb();
+            var list = db.Queryable<Student>().Where(it => MyToString(it.Id) == "1302583").ToList();
+            var sql = db.Queryable<Student>().Where(it => MyToString(it.Id) == "1302583").ToSql();
+            Console.WriteLine(sql);
+        }
+    }
+}
diff --git a/Src/Asp.NetCore2/SqlSeverTest/SqlSeverTest/Program.cs b/Src/Asp.NetCore2/SqlSeverTest/SqlSeverTest/Program.cs
index 8fad6514c..bf77f7c1e 100644
--- a/Src/Asp.NetCore2/SqlSeverTest/SqlSeverTest/Program.cs
+++ b/Src/Asp.NetCore2/SqlSeverTest/SqlSeverTest/Program.cs
@@ -39,6 +39,7 @@ namespace SqlSeverTest
             OrmTest.Demo.CodeFirst.Init();
             OrmTest.Demo.MasterSlave.Init();
             OrmTest.Demo.SharedConnection.Init();
+            OrmTest.Demo.ExtSqlFun.Init();
         }
     }
 }