diff --git a/src/ShardingCore/Core/Collections/SafeReadAppendList.cs b/src/ShardingCore/Core/Collections/SafeReadAppendList.cs
index eccb525e..3521f9b9 100644
--- a/src/ShardingCore/Core/Collections/SafeReadAppendList.cs
+++ b/src/ShardingCore/Core/Collections/SafeReadAppendList.cs
@@ -23,11 +23,11 @@ namespace ShardingCore.Core.Collections
         {
             get
             {
-                if (_copyList?.Count != _list.Count)
+                if (_copyList.Count != _list.Count)
                 {
                     lock (COPY_LOCK)
                     {
-                        if (_copyList?.Count != _list.Count)
+                        if (_copyList.Count != _list.Count)
                         {
                             _copyList = _list.ToList();
                         }
@@ -38,7 +38,7 @@ namespace ShardingCore.Core.Collections
             }
         }
 
-        public List<T> _copyList;
+        public List<T> _copyList=new List<T>(0);
 
         public void Append(T value)
         {
diff --git a/test/ShardingCore.CommonTest/CommonTest.cs b/test/ShardingCore.CommonTest/CommonTest.cs
new file mode 100644
index 00000000..a7bbf758
--- /dev/null
+++ b/test/ShardingCore.CommonTest/CommonTest.cs
@@ -0,0 +1,37 @@
+using System.Diagnostics;
+using ShardingCore.Core.Collections;
+using Xunit;
+
+namespace ShardingCore.CommonTest
+{
+    public class CommonTest
+    {
+        [Fact]
+        public void TestList()
+        {
+            var list = new List<string>(){"1","2","3"};
+            var safeReadAppendList = new SafeReadAppendList<string>(list);
+            Assert.True(safeReadAppendList.CopyList.Count==3);
+            for (int i = 0; i < list.Count; i++)
+            {
+               Assert.Equal(list[i],safeReadAppendList.CopyList[i]);
+            }
+            list.Add("4");
+            safeReadAppendList.Append("4");
+            Assert.True(safeReadAppendList.CopyList.Count==4);
+            for (int i = 0; i < list.Count; i++)
+            {
+                Assert.Equal(list[i],safeReadAppendList.CopyList[i]);
+            }
+
+            Stopwatch sp = Stopwatch.StartNew();
+            for (int i = 0; i < 1000000000; i++)
+            {
+                var copyListCount = safeReadAppendList.CopyList.Count;
+            }
+            sp.Stop();
+            Console.WriteLine(sp.ElapsedMilliseconds);
+        }
+    }
+    
+}