diff --git a/format/rtmp/rtmp.go b/format/rtmp/rtmp.go
index 9c71205..db02f69 100644
--- a/format/rtmp/rtmp.go
+++ b/format/rtmp/rtmp.go
@@ -1037,6 +1037,7 @@ func (self *Conn) writeAVTag(tag flvio.Tag, ts int32) (err error) {
 		return
 	}
 	_, err = self.bufw.Write(data)
+	err = self.bufw.Flush()
 	return
 }