diff --git a/trunk/conf/srs.conf b/trunk/conf/srs.conf
index 232c1238e..6ae16e04c 100755
--- a/trunk/conf/srs.conf
+++ b/trunk/conf/srs.conf
@@ -4,8 +4,8 @@ listen              1935;
 # some client does not support chunk size change,
 # however, most clients supports it and it can improve 
 # performance about 10%.
-# default: 4096
-chunk_size          65000;
+# default: 60000
+chunk_size          60000;
 # the logs dir.
 # if enabled ffmpeg, each stracoding stream will create a log file.
 # default: ./objs/logs
@@ -26,7 +26,7 @@ vhost __defaultVhost__ {
 # for which cannot identify the required vhost.
 # for default demo.
 vhost demo.srs.com {
-    chunk_size      4096;
+    chunk_size      60000;
     enabled         on;
     gop_cache       on;
     queue_length    30;
diff --git a/trunk/src/core/srs_core_config.hpp b/trunk/src/core/srs_core_config.hpp
index 3cd693275..4bbe122eb 100644
--- a/trunk/src/core/srs_core_config.hpp
+++ b/trunk/src/core/srs_core_config.hpp
@@ -57,7 +57,8 @@ CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 // the interval in seconds for bandwidth check
 #define SRS_CONF_DEFAULT_BANDWIDTH_LIMIT_KBPS 1000
 
-#define SRS_CONF_DEFAULT_CHUNK_SIZE 4096
+// the default chunk size for system.
+#define SRS_CONF_DEFAULT_CHUNK_SIZE 60000
 
 #define SRS_STAGE_PLAY_USER_INTERVAL_MS 1300
 #define SRS_STAGE_PUBLISH_USER_INTERVAL_MS 1100
diff --git a/trunk/src/core/srs_core_rtmp.cpp b/trunk/src/core/srs_core_rtmp.cpp
index 4164436d2..bf67fb9fc 100644
--- a/trunk/src/core/srs_core_rtmp.cpp
+++ b/trunk/src/core/srs_core_rtmp.cpp
@@ -391,12 +391,44 @@ int SrsRtmpClient::play(string stream, int stream_id)
 		}
 	}
 	
+	// SetChunkSize
+	if (true) {
+		SrsCommonMessage* msg = new SrsCommonMessage();
+		SrsSetChunkSizePacket* pkt = new SrsSetChunkSizePacket();
+	
+		pkt->chunk_size = SRS_CONF_DEFAULT_CHUNK_SIZE;
+		msg->set_packet(pkt, 0);
+		
+		if ((ret = protocol->send_message(msg)) != ERROR_SUCCESS) {
+			srs_error("send set chunk size failed. "
+				"stream=%s, chunk_size=%d, ret=%d", 
+				stream.c_str(), SRS_CONF_DEFAULT_CHUNK_SIZE, ret);
+			return ret;
+		}
+	}
+	
 	return ret;
 }
 
 int SrsRtmpClient::publish(string stream, int stream_id)
 {
 	int ret = ERROR_SUCCESS;
+	
+	// SetChunkSize
+	if (true) {
+		SrsCommonMessage* msg = new SrsCommonMessage();
+		SrsSetChunkSizePacket* pkt = new SrsSetChunkSizePacket();
+	
+		pkt->chunk_size = SRS_CONF_DEFAULT_CHUNK_SIZE;
+		msg->set_packet(pkt, 0);
+		
+		if ((ret = protocol->send_message(msg)) != ERROR_SUCCESS) {
+			srs_error("send set chunk size failed. "
+				"stream=%s, chunk_size=%d, ret=%d", 
+				stream.c_str(), SRS_CONF_DEFAULT_CHUNK_SIZE, ret);
+			return ret;
+		}
+	}
 
 	// publish(stream)
 	if (true) {