diff --git a/README.md b/README.md
index 26b7db284..5f7c127cb 100755
--- a/README.md
+++ b/README.md
@@ -174,6 +174,7 @@ The ports used by SRS:
 
 ## V4 changes
 
+* v4.0, 2021-05-21, RTC: Refine sdk, migrate from onaddstream to ontrack. 4.0.120
 * v4.0, 2021-05-21, Tools: Refine configure options. 4.0.119
 * v4.0, 2021-05-20, Fix build fail when disable RTC by --rtc=off. 4.0.118
 * v4.0, 2021-05-19, Fix [#2362][bug #2362]: Allow WebRTC to play before publishing, for GB28181 as such. 4.0.117
diff --git a/trunk/research/players/js/srs.sdk.js b/trunk/research/players/js/srs.sdk.js
index 4b030542d..860735413 100644
--- a/trunk/research/players/js/srs.sdk.js
+++ b/trunk/research/players/js/srs.sdk.js
@@ -62,6 +62,9 @@ function SrsRtcPublisherAsync() {
         // @see https://developer.mozilla.org/en-US/docs/Web/API/RTCPeerConnection/addStream#Migrating_to_addTrack
         stream.getTracks().forEach(function (track) {
             self.pc.addTrack(track);
+
+            // Notify about local track when stream is ok.
+            self.ontrack && self.ontrack({track: track});
         });
 
         var offer = await self.pc.createOffer();
@@ -94,9 +97,6 @@ function SrsRtcPublisherAsync() {
         );
         session.simulator = conf.schema + '//' + conf.urlObject.server + ':' + conf.port + '/rtc/v1/nack/';
 
-        // Notify about local stream when success.
-        self.onaddstream && self.onaddstream({stream: stream});
-
         return session;
     };
 
@@ -107,7 +107,10 @@ function SrsRtcPublisherAsync() {
     };
 
     // The callback when got local stream.
-    self.onaddstream = function (event) {
+    // @see https://developer.mozilla.org/en-US/docs/Web/API/RTCPeerConnection/addStream#Migrating_to_addTrack
+    self.ontrack = function (event) {
+        // Add track to stream of SDK.
+        self.stream.addTrack(event.track);
     };
 
     // Internal APIs.
@@ -253,6 +256,11 @@ function SrsRtcPublisherAsync() {
 
     self.pc = new RTCPeerConnection(null);
 
+    // To keep api consistent between player and publisher.
+    // @see https://developer.mozilla.org/en-US/docs/Web/API/RTCPeerConnection/addStream#Migrating_to_addTrack
+    // @see https://webrtc.org/getting-started/media-devices
+    self.stream = new MediaStream();
+
     return self;
 }
 
@@ -324,8 +332,12 @@ function SrsRtcPlayerAsync() {
         self.pc = null;
     };
 
-    // The callback when got remote stream.
-    self.onaddstream = function (event) {};
+    // The callback when got remote track.
+    // Note that the onaddstream is deprecated, @see https://developer.mozilla.org/en-US/docs/Web/API/RTCPeerConnection/onaddstream
+    self.ontrack = function (event) {
+        // https://webrtc.org/getting-started/remote-streams
+        self.stream.addTrack(event.track);
+    };
 
     // Internal APIs.
     self.__internal = {
@@ -469,9 +481,14 @@ function SrsRtcPlayerAsync() {
     };
 
     self.pc = new RTCPeerConnection(null);
-    self.pc.onaddstream = function (event) {
-        if (self.onaddstream) {
-            self.onaddstream(event);
+
+    // Create a stream to add track to the stream, @see https://webrtc.org/getting-started/remote-streams
+    self.stream = new MediaStream();
+
+    // https://developer.mozilla.org/en-US/docs/Web/API/RTCPeerConnection/ontrack
+    self.pc.ontrack = function(event) {
+        if (self.ontrack) {
+            self.ontrack(event);
         }
     };
 
diff --git a/trunk/research/players/rtc_player.html b/trunk/research/players/rtc_player.html
index bd3d668c9..0a4c3a3a5 100644
--- a/trunk/research/players/rtc_player.html
+++ b/trunk/research/players/rtc_player.html
@@ -73,15 +73,14 @@
             if (sdk) {
                 sdk.close();
             }
-
             sdk = new SrsRtcPlayerAsync();
-            sdk.onaddstream = function (event) {
-                console.log('Start play, event: ', event);
-                $('#rtc_media_player').prop('srcObject', event.stream);
-            };
 
-            // For example:
-            //      webrtc://r.ossrs.net/live/livestream
+            // https://webrtc.org/getting-started/remote-streams
+            $('#rtc_media_player').prop('srcObject', sdk.stream);
+            // Optional callback, SDK will add track to stream.
+            // sdk.ontrack = function (event) { console.log('Got track', event); sdk.stream.addTrack(event.track); };
+
+            // For example: webrtc://r.ossrs.net/live/livestream
             var url = $("#txt_url").val();
             sdk.play(url).then(function(session){
                 $('#sessionid').html(session.sessionid);
diff --git a/trunk/research/players/rtc_publisher.html b/trunk/research/players/rtc_publisher.html
index 3aa9d0e66..1159d0e8f 100644
--- a/trunk/research/players/rtc_publisher.html
+++ b/trunk/research/players/rtc_publisher.html
@@ -78,12 +78,13 @@
             if (sdk) {
                 sdk.close();
             }
-
             sdk = new SrsRtcPublisherAsync();
-            sdk.onaddstream = function (event) {
-                console.log('Start publish, event: ', event);
-                $('#rtc_media_player').prop('srcObject', event.stream);
-            };
+
+            // User should set the stream when publish is done, @see https://webrtc.org/getting-started/media-devices
+            // However SRS SDK provides a consist API like https://webrtc.org/getting-started/remote-streams
+            $('#rtc_media_player').prop('srcObject', sdk.stream);
+            // Optional callback, SDK will add track to stream.
+            // sdk.ontrack = function (event) { console.log('Got track', event); sdk.stream.addTrack(event.track); };
 
             // https://developer.mozilla.org/en-US/docs/Web/Media/Formats/WebRTC_codecs#getting_the_supported_codecs
             sdk.pc.onicegatheringstatechange = function (event) {
@@ -93,8 +94,7 @@
                 }
             };
 
-            // For example:
-            //      webrtc://r.ossrs.net/live/livestream
+            // For example: webrtc://r.ossrs.net/live/livestream
             var url = $("#txt_url").val();
             sdk.publish(url).then(function(session){
                 $('#sessionid').html(session.sessionid);
diff --git a/trunk/src/core/srs_core_version4.hpp b/trunk/src/core/srs_core_version4.hpp
index 0e40b98ec..f4e0917d0 100644
--- a/trunk/src/core/srs_core_version4.hpp
+++ b/trunk/src/core/srs_core_version4.hpp
@@ -26,6 +26,6 @@
 
 #define VERSION_MAJOR       4
 #define VERSION_MINOR       0
-#define VERSION_REVISION    119
+#define VERSION_REVISION    120
 
 #endif