diff --git a/README.md b/README.md
index 6675ca4..d3d17bd 100644
--- a/README.md
+++ b/README.md
@@ -89,11 +89,6 @@ if you want to deactivate all, please clear all textboxes.
 
 Please visit [Servers] for more information.
 
-#### Portable Mode
-
-If you want to put all temporary files into shadowsocks/temp folder instead of
-system temp folder, create a `shadowsocks_portable_mode.txt` into shadowsocks folder.
-
 #### Develop
 
 [Visual Studio 2015] & [.NET Framework 4.6.2 Developer Pack] are required.
diff --git a/shadowsocks-csharp/Controller/Service/PrivoxyRunner.cs b/shadowsocks-csharp/Controller/Service/PrivoxyRunner.cs
index 970473b..061215e 100644
--- a/shadowsocks-csharp/Controller/Service/PrivoxyRunner.cs
+++ b/shadowsocks-csharp/Controller/Service/PrivoxyRunner.cs
@@ -121,21 +121,13 @@ namespace Shadowsocks.Controller
         {
             try
             {
-                if (Utils.IsPortableMode())
-                {
-                    /*
-                     * Under PortableMode, we could identify it by the path of ss_privoxy.exe.
-                     */
-                    var path = process.MainModule.FileName;
+                /*
+                 * Under PortableMode, we could identify it by the path of ss_privoxy.exe.
+                 */
+                var path = process.MainModule.FileName;
 
-                    return Utils.GetTempPath("ss_privoxy.exe").Equals(path);
-                }
-                else
-                {
-                    var cmd = process.GetCommandLine();
+                return Utils.GetTempPath("ss_privoxy.exe").Equals(path);
 
-                    return cmd.Contains(_uniqueConfigFile);
-                }
             }
             catch (Exception ex)
             {
diff --git a/shadowsocks-csharp/Util/Util.cs b/shadowsocks-csharp/Util/Util.cs
index f733193..e428568 100755
--- a/shadowsocks-csharp/Util/Util.cs
+++ b/shadowsocks-csharp/Util/Util.cs
@@ -25,43 +25,26 @@ namespace Shadowsocks.Util
 
     public static class Utils
     {
-        private static bool? _portableMode;
-        private static string TempPath = null;
-
-        public static bool IsPortableMode()
-        {
-            if (!_portableMode.HasValue)
-            {
-                _portableMode = File.Exists(Path.Combine(Application.StartupPath, "shadowsocks_portable_mode.txt"));
-            }
-
-            return _portableMode.Value;
-        }
+        private static string _tempPath = null;
 
         // return path to store temporary files
         public static string GetTempPath()
         {
-            if (TempPath == null)
+            if (_tempPath == null)
             {
-                if (IsPortableMode())
-                    try
-                    {
-                        Directory.CreateDirectory(Path.Combine(Application.StartupPath, "temp"));
-                    }
-                    catch (Exception e)
-                    {
-                        TempPath = Path.GetTempPath();
-                        Logging.LogUsefulException(e);
-                    }
-                    finally
-                    {
-                        // don't use "/", it will fail when we call explorer /select xxx/temp\xxx.log
-                        TempPath = Path.Combine(Application.StartupPath, "temp");
-                    }
-                else
-                    TempPath = Path.GetTempPath();
+                try
+                {
+                    Directory.CreateDirectory(Path.Combine(Application.StartupPath, "ss_win_temp"));
+                    // don't use "/", it will fail when we call explorer /select xxx/ss_win_temp\xxx.log
+                    _tempPath = Path.Combine(Application.StartupPath, "ss_win_temp");
+                }
+                catch (Exception e)
+                {
+                    Logging.Error(e);
+                    throw;
+                }
             }
-            return TempPath;
+            return _tempPath;
         }
 
         // return a full path with filename combined which pointed to the temporary directory