diff --git a/shadowsocks-csharp/Encryptor.cs b/shadowsocks-csharp/Encryptor.cs
index ddce03c3..c40d9212 100755
--- a/shadowsocks-csharp/Encryptor.cs
+++ b/shadowsocks-csharp/Encryptor.cs
@@ -1,6 +1,5 @@
 using System;
 using System.Collections.Generic;
-using System.Linq;
 using System.Text;
 using System.Security.Cryptography;
 
diff --git a/shadowsocks-csharp/Form1.cs b/shadowsocks-csharp/Form1.cs
index 542e18c9..6e1f20a6 100755
--- a/shadowsocks-csharp/Form1.cs
+++ b/shadowsocks-csharp/Form1.cs
@@ -3,7 +3,6 @@ using System.Collections.Generic;
 using System.ComponentModel;
 using System.Data;
 using System.Drawing;
-using System.Linq;
 using System.Text;
 using System.Windows.Forms;
 
diff --git a/shadowsocks-csharp/Local.cs b/shadowsocks-csharp/Local.cs
index 14dd7eab..cfe95ae9 100755
--- a/shadowsocks-csharp/Local.cs
+++ b/shadowsocks-csharp/Local.cs
@@ -1,6 +1,5 @@
 using System;
 using System.Collections.Generic;
-using System.Linq;
 using System.Text;
 using System.Net.Sockets;
 using System.Net;
diff --git a/shadowsocks-csharp/Program.cs b/shadowsocks-csharp/Program.cs
index d21d81aa..c3f34158 100755
--- a/shadowsocks-csharp/Program.cs
+++ b/shadowsocks-csharp/Program.cs
@@ -1,6 +1,5 @@
 using System;
 using System.Collections.Generic;
-using System.Linq;
 using System.Windows.Forms;
 
 namespace shadowsocks_csharp
diff --git a/shadowsocks-csharp/Test.cs b/shadowsocks-csharp/Test.cs
index 3d174d52..ec255550 100755
--- a/shadowsocks-csharp/Test.cs
+++ b/shadowsocks-csharp/Test.cs
@@ -1,6 +1,5 @@
 using System;
 using System.Collections.Generic;
-using System.Linq;
 using System.Text;
 using System.Diagnostics;
 
diff --git a/shadowsocks-csharp/shadowsocks-csharp.csproj b/shadowsocks-csharp/shadowsocks-csharp.csproj
index 09d36023..5359532b 100755
--- a/shadowsocks-csharp/shadowsocks-csharp.csproj
+++ b/shadowsocks-csharp/shadowsocks-csharp.csproj
@@ -10,7 +10,7 @@
     <AppDesignerFolder>Properties</AppDesignerFolder>
     <RootNamespace>shadowsocks_csharp</RootNamespace>
     <AssemblyName>shadowsocks-csharp</AssemblyName>
-    <TargetFrameworkVersion>v3.5</TargetFrameworkVersion>
+    <TargetFrameworkVersion>v2.0</TargetFrameworkVersion>
     <FileAlignment>512</FileAlignment>
     <StartupObject>
     </StartupObject>
@@ -34,15 +34,6 @@
   </PropertyGroup>
   <ItemGroup>
     <Reference Include="System" />
-    <Reference Include="System.Core">
-      <RequiredTargetFramework>3.5</RequiredTargetFramework>
-    </Reference>
-    <Reference Include="System.Xml.Linq">
-      <RequiredTargetFramework>3.5</RequiredTargetFramework>
-    </Reference>
-    <Reference Include="System.Data.DataSetExtensions">
-      <RequiredTargetFramework>3.5</RequiredTargetFramework>
-    </Reference>
     <Reference Include="System.Data" />
     <Reference Include="System.Deployment" />
     <Reference Include="System.Drawing" />