diff --git a/src/main/res/values-zh/strings.xml b/src/main/res/values-zh/strings.xml
index da320a87..02d6f29d 100755
--- a/src/main/res/values-zh/strings.xml
+++ b/src/main/res/values-zh/strings.xml
@@ -72,6 +72,9 @@
   <string name="ipv6">IPv6 路由</string>
   <string name="ipv6_summary">向远程服务器转发 IPv6 流量</string>
 
+  <string name="stat">网络流量</string>
+  <string name="stat_summary">发送:\t%1$s\t|\t接收:\t%2$s\n上传:\t%3$s\t|\t下载:\t%4$s</string>
+
   <!-- profile -->
   <string name="add_profile_dialog">为影梭添加此配置文件？</string>
   <string name="add_profile_methods_scan_qr_code">扫描二维码</string>
diff --git a/src/main/res/values/strings.xml b/src/main/res/values/strings.xml
index 597957e6..ba72d186 100644
--- a/src/main/res/values/strings.xml
+++ b/src/main/res/values/strings.xml
@@ -12,6 +12,8 @@
   <string name="nat">NAT mode (deprecated)</string>
   <string name="nat_summary">Use NAT mode instead of VPN mode</string>
   <string name="nat_summary_no_root">NAT mode is disabled without root</string>
+  <string name="stat">Network Traffic</string>
+  <string name="stat_summary">Send:\t%1$s\t|\tReceive:\t%2$s\nUpload:\t%3$s\t|\tDownload:\t%4$s</string>
 
   <!-- proxy category -->
   <string name="proxy_cat">Server Settings</string>
diff --git a/src/main/res/xml/pref_all.xml b/src/main/res/xml/pref_all.xml
index 637eebaa..82412e04 100644
--- a/src/main/res/xml/pref_all.xml
+++ b/src/main/res/xml/pref_all.xml
@@ -8,6 +8,8 @@
             <intent android:action="com.github.shadowsocks.ProfileManagerActivity"/>
         </Preference>
 
+        <Preference android:key="stat" android:title="@string/stat"/>
+
     </PreferenceCategory>
 
     <PreferenceCategory
diff --git a/src/main/scala/com/github/shadowsocks/Shadowsocks.scala b/src/main/scala/com/github/shadowsocks/Shadowsocks.scala
index 1aa91273..0a9dcd47 100644
--- a/src/main/scala/com/github/shadowsocks/Shadowsocks.scala
+++ b/src/main/scala/com/github/shadowsocks/Shadowsocks.scala
@@ -40,7 +40,7 @@ package com.github.shadowsocks
 
 import java.io.{FileOutputStream, IOException, InputStream, OutputStream}
 import java.util
-import java.util.Locale
+import java.util.{Locale, Timer, TimerTask}
 
 import android.app.backup.BackupManager
 import android.app.{Activity, ProgressDialog}
@@ -147,7 +147,7 @@ class Shadowsocks
   extends AppCompatActivity {
 
   // Variables
-  private var serviceStarted = false
+  var serviceStarted = false
   var fab: FloatingActionButton = _
   var fabProgressCircle: FABProgressCircle = _
   var progressDialog: ProgressDialog = _
@@ -156,6 +156,8 @@ class Shadowsocks
   var prepared = false
   var currentProfile = new Profile
   var vpnEnabled = -1
+  var timer: Timer = null
+  val TIMER_INTERVAL = 1 // sec
 
   // Services
   var currentServiceName = classOf[ShadowsocksNatService].getName
@@ -465,6 +467,24 @@ class Shadowsocks
 
     // Check if current profile changed
     if (ShadowsocksApplication.profileId != currentProfile.id) reloadProfile()
+
+    // initialize timer
+    val task = new TimerTask {
+      def run() {
+        TrafficMonitor.update()
+        val pm = getSystemService(Context.POWER_SERVICE).asInstanceOf[PowerManager]
+        if (pm.isScreenOn) {
+          val trafficStat = getString(R.string.stat_summary).formatLocal(Locale.ENGLISH,
+            TrafficMonitor.getTxRate, TrafficMonitor.getRxRate,
+            TrafficMonitor.getTxTotal, TrafficMonitor.getRxTotal)
+            handler.post(() => {
+              preferences.findPreference(Key.stat).setSummary(trafficStat)
+            })
+        }
+      }
+    }
+    timer = new Timer(true)
+    timer.schedule(task, TIMER_INTERVAL * 1000, TIMER_INTERVAL * 1000)
   }
 
   private def setPreferenceEnabled(enabled: Boolean) {
@@ -510,6 +530,12 @@ class Shadowsocks
   override def onStop() {
     super.onStop()
     clearDialog()
+
+    // reset timer
+    if (timer != null) {
+      timer.cancel()
+      timer = null
+    }
   }
 
   override def onDestroy() {
diff --git a/src/main/scala/com/github/shadowsocks/ShadowsocksNatService.scala b/src/main/scala/com/github/shadowsocks/ShadowsocksNatService.scala
index 52e11c9d..72bf9d7b 100644
--- a/src/main/scala/com/github/shadowsocks/ShadowsocksNatService.scala
+++ b/src/main/scala/com/github/shadowsocks/ShadowsocksNatService.scala
@@ -420,6 +420,8 @@ class ShadowsocksNatService extends Service with BaseService {
 
   override def startRunner(c: Config) {
 
+    TrafficMonitor.reset()
+
     config = c
 
     // register close receiver
@@ -509,6 +511,8 @@ class ShadowsocksNatService extends Service with BaseService {
 
   override def stopRunner() {
 
+    TrafficMonitor.reset()
+
     // channge the state
     changeState(State.STOPPING)
 
diff --git a/src/main/scala/com/github/shadowsocks/ShadowsocksVpnService.scala b/src/main/scala/com/github/shadowsocks/ShadowsocksVpnService.scala
index 8b78ba7c..082cec64 100644
--- a/src/main/scala/com/github/shadowsocks/ShadowsocksVpnService.scala
+++ b/src/main/scala/com/github/shadowsocks/ShadowsocksVpnService.scala
@@ -144,6 +144,8 @@ class ShadowsocksVpnService extends VpnService with BaseService {
 
   override def stopRunner() {
 
+    TrafficMonitor.reset()
+
     if (vpnThread != null) {
       vpnThread.stopThread()
       vpnThread = null
@@ -217,6 +219,8 @@ class ShadowsocksVpnService extends VpnService with BaseService {
 
   override def startRunner(c: Config) {
 
+    TrafficMonitor.reset()
+
     vpnThread = new ShadowsocksVpnThread(this)
     vpnThread.start()
 
diff --git a/src/main/scala/com/github/shadowsocks/utils/Constants.scala b/src/main/scala/com/github/shadowsocks/utils/Constants.scala
index 07b645fd..c207e08d 100644
--- a/src/main/scala/com/github/shadowsocks/utils/Constants.scala
+++ b/src/main/scala/com/github/shadowsocks/utils/Constants.scala
@@ -68,6 +68,7 @@ object Key {
   val profiles = "profiles"
   val isNAT = "isNAT"
   val route = "route"
+  val stat = "stat"
 
   val isRunning = "isRunning"
   val isAutoConnect = "isAutoConnect"
diff --git a/src/main/scala/com/github/shadowsocks/utils/TrafficMonitor.scala b/src/main/scala/com/github/shadowsocks/utils/TrafficMonitor.scala
index d26c236d..d3b7c478 100644
--- a/src/main/scala/com/github/shadowsocks/utils/TrafficMonitor.scala
+++ b/src/main/scala/com/github/shadowsocks/utils/TrafficMonitor.scala
@@ -38,16 +38,16 @@ object TrafficMonitor {
     }
   }
 
-  def updateTraffic() {
+  def update() {
     val now = getTraffic
-    txRate = ((now.tx - last.tx) / 1024 / (now.timestamp - last.timestamp))
-    rxRate = ((now.rx - last.rx) / 1024 / (now.timestamp - last.timestamp))
+    txRate = (now.tx - last.tx) / (now.timestamp - last.timestamp)
+    rxRate = (now.rx - last.rx) / (now.timestamp - last.timestamp)
     txTotal += (now.tx - last.tx) / 1024
     rxTotal += (now.rx - last.rx) / 1024
     last = now
   }
 
-  def resetTraffic() {
+  def reset() {
     txRate = 0
     rxRate = 0
     txTotal = 0