diff --git a/LinqStudy.Test/LinqToObject/ConcatTest.cs b/LinqStudy.Test/LinqToObject/ConcatTest.cs
deleted file mode 100644
index ed3cb75..0000000
--- a/LinqStudy.Test/LinqToObject/ConcatTest.cs
+++ /dev/null
@@ -1,40 +0,0 @@
-using System;
-using System.Collections;
-using System.Collections.Generic;
-using System.Linq;
-
-using Xunit;
-using LinqStudy;
-
-namespace LinqStudy.Test.LinqToObject
-{
-    ///<summary>
-    /// 串联操作
-    ///<summary>
-    public class ConcatTest
-    {
-        ///<summary>
-        /// Concat：将两个序列合并成一个序列，不去重。与Union不同。
-        ///<summary>
-        public void Concat_Test()
-        {
-            List<Person> peoples1 = new List<Person>()
-            {
-                new Person(){ Id=2, Name="小龙女", Age=28},
-                new Person(){ Id=4, Name="杨过", Age=32},
-            };
-
-            List<Person> peoples2 = new List<Person>()
-            {
-                new Person(){ Id=2, Name="小龙女", Age=28},
-                new Person(){ Id=3, Name="云花公主", Age=16},
-            };
-
-            var concatAct = peoples1.Concat(peoples2);
-
-            var totalCount = concatAct.Count();
-
-            Assert.Equal(4, totalCount);
-        }
-    }
-}
\ No newline at end of file
diff --git a/LinqStudy.Test/LinqToObject/JoinTest.cs b/LinqStudy.Test/LinqToObject/JoinTest.cs
new file mode 100644
index 0000000..f4fa033
--- /dev/null
+++ b/LinqStudy.Test/LinqToObject/JoinTest.cs
@@ -0,0 +1,61 @@
+using System;
+using System.Collections;
+using System.Collections.Generic;
+using System.Linq;
+
+using Xunit;
+using LinqStudy;
+
+namespace LinqStudy.Test.LinqToObject
+{
+    ///<summary>
+    /// 联接操作:将一个数据源对象与另一个数据源对象进行关联或联合的操作。
+    /// 延迟执行
+    /// 数据源为null,均引发异常
+    ///<summary>
+    public class JoinTest
+    {
+        #region Jion
+        /// <summary>
+        /// Jion：将一个数据源与另一个数据源相联接，根据两个数据源中相等的值进行匹配；
+        ///       类似T-SQL中的Inner Join
+        /// 延迟执行
+        /// </summary>
+        [Fact]
+        public void Jion_Test()
+        {
+            List<Person> peoples = new List<Person>()
+            {
+                new Person(){ Id=1, Name="小龙女",Age=18 },
+                new Person(){ Id=2, Name="郭靖",Age=28 },
+            };
+
+            List<Teacher> teachers = new List<Teacher>()
+            {
+                new Teacher(){ Id=1, Name="杨过老师",Hometown=new Hometown(){ Province="终南山",City="古墓"} },
+                new Teacher(){ Id=2, Name="郭老师",Hometown=new Hometown(){ Province="湖北省",City="襄阳"} },
+                new Teacher(){ Id=3, Name="金轮法师",Hometown=new Hometown(){ Province="西藏",City="游民"} },
+            };
+
+            var jionItem = peoples.Join
+            (
+                teachers, p => p.Id, 
+                t => t.Id, 
+                (p, t) => new
+                {
+                    Id = 1,
+                    Name = p.Name + "-" + t.Name,
+                    Age = 18,
+                    Hometown = t.Hometown
+                }
+            )
+            .ToList();
+
+            Assert.Equal(2, jionItem.Count);
+        }
+        #endregion
+
+        #region GroupJion
+        #endregion
+    }
+}
\ No newline at end of file
diff --git a/LinqStudy.Test/LinqToObject/OrderTest.cs b/LinqStudy.Test/LinqToObject/OrderTest.cs
index f74bec9..c4b6f75 100644
--- a/LinqStudy.Test/LinqToObject/OrderTest.cs
+++ b/LinqStudy.Test/LinqToObject/OrderTest.cs
@@ -58,7 +58,7 @@ namespace LinqStudy.Test.LinqToObject
             var lastName = oprationItem.Last().Name;
 
             Assert.Equal("张三", firtName);
-            Assert.Equal("王五", lastName);
+            Assert.Equal("赵六", lastName);
         }
 
         /// <summary>
diff --git a/LinqStudy.Test/LinqToObject/SetsTest.cs b/LinqStudy.Test/LinqToObject/SetsTest.cs
index 86e5380..12d8ff8 100644
--- a/LinqStudy.Test/LinqToObject/SetsTest.cs
+++ b/LinqStudy.Test/LinqToObject/SetsTest.cs
@@ -381,5 +381,37 @@ namespace LinqStudy.Test.LinqToObject
             Assert.Equal("杨过", iexcepItemName);
         }
         #endregion
+
+        #region Concat
+        ///<summary>
+        /// 串联操作
+        ///<summary>
+        public class ConcatTest
+        {
+            ///<summary>
+            /// Concat：将两个序列合并成一个序列，不去重。与Union不同。
+            ///<summary>
+            public void Concat_Test()
+            {
+                List<Person> peoples1 = new List<Person>()
+            {
+                new Person(){ Id=2, Name="小龙女", Age=28},
+                new Person(){ Id=4, Name="杨过", Age=32},
+            };
+
+                List<Person> peoples2 = new List<Person>()
+            {
+                new Person(){ Id=2, Name="小龙女", Age=28},
+                new Person(){ Id=3, Name="云花公主", Age=16},
+            };
+
+                var concatAct = peoples1.Concat(peoples2);
+
+                var totalCount = concatAct.Count();
+
+                Assert.Equal(4, totalCount);
+            }
+        }
+        #endregion
     }
 }
\ No newline at end of file