diff --git a/srt/PacketQueue.cpp b/srt/PacketQueue.cpp
index 37980ae0..9349f050 100644
--- a/srt/PacketQueue.cpp
+++ b/srt/PacketQueue.cpp
@@ -237,11 +237,16 @@ std::string PacketQueue::dump() {
 
 //////////////////// PacketRecvQueue //////////////////////////////////
 
-PacketRecvQueue::PacketRecvQueue(uint32_t max_size, uint32_t init_seq, uint32_t latency)
+PacketRecvQueue::PacketRecvQueue(uint32_t max_size, uint32_t init_seq, uint32_t latency,uint32_t flag)
     : _pkt_cap(max_size)
     , _pkt_latency(latency)
     , _pkt_expected_seq(init_seq)
-    , _pkt_buf(max_size) {}
+    , _pkt_buf(max_size)
+    , _srt_flag(flag) {}
+
+bool  PacketRecvQueue::TLPKTDrop(){
+    return (_srt_flag&HSExtMessage::HS_EXT_MSG_TLPKTDROP) && (_srt_flag &HSExtMessage::HS_EXT_MSG_TSBPDRCV);
+}
 bool PacketRecvQueue::inputPacket(DataPacket::Ptr pkt, std::list<DataPacket::Ptr> &out) {
     // TraceL << dump() << " seq:" << pkt->packet_seq_number;
     while (_size > 0 && _start == _end) {
@@ -265,7 +270,7 @@ bool PacketRecvQueue::inputPacket(DataPacket::Ptr pkt, std::list<DataPacket::Ptr
         _start = (_start + 1) % _pkt_cap;
         it = _pkt_buf[_start];
     }
-    while (timeLatency() > _pkt_latency) {
+    while (timeLatency() > _pkt_latency && TLPKTDrop()) {
         it = _pkt_buf[_start];
         if (it) {
             _pkt_buf[_start] = nullptr;
diff --git a/srt/PacketQueue.hpp b/srt/PacketQueue.hpp
index d3e224c6..95ae9c66 100644
--- a/srt/PacketQueue.hpp
+++ b/srt/PacketQueue.hpp
@@ -65,7 +65,7 @@ class PacketRecvQueue : public PacketQueueInterface {
 public:
     using Ptr = std::shared_ptr<PacketRecvQueue>;
 
-    PacketRecvQueue(uint32_t max_size, uint32_t init_seq, uint32_t latency);
+    PacketRecvQueue(uint32_t max_size, uint32_t init_seq, uint32_t latency,uint32_t flag = 0xbf);
     ~PacketRecvQueue() = default;
     bool inputPacket(DataPacket::Ptr pkt, std::list<DataPacket::Ptr> &out);
 
@@ -85,12 +85,15 @@ private:
     void insertToCycleBuf(DataPacket::Ptr pkt, uint32_t diff);
     DataPacket::Ptr getFirst();
     DataPacket::Ptr getLast();
+    bool TLPKTDrop();
 
 private:
     uint32_t _pkt_cap;
     uint32_t _pkt_latency;
     uint32_t _pkt_expected_seq;
 
+    uint32_t _srt_flag;
+
     std::vector<DataPacket::Ptr> _pkt_buf;
     uint32_t _start = 0;
     uint32_t _end = 0;
diff --git a/srt/PacketSendQueue.cpp b/srt/PacketSendQueue.cpp
index 92730a4a..06beddde 100644
--- a/srt/PacketSendQueue.cpp
+++ b/srt/PacketSendQueue.cpp
@@ -2,9 +2,10 @@
 
 namespace SRT {
 
-PacketSendQueue::PacketSendQueue(uint32_t max_size, uint32_t latency)
+PacketSendQueue::PacketSendQueue(uint32_t max_size, uint32_t latency,uint32_t flag)
     : _pkt_cap(max_size)
-    , _pkt_latency(latency) {}
+    , _pkt_latency(latency)
+    , _srt_flag(flag) {}
 
 bool PacketSendQueue::drop(uint32_t num) {
     decltype(_pkt_cache.begin()) it;
@@ -24,12 +25,16 @@ bool PacketSendQueue::inputPacket(DataPacket::Ptr pkt) {
     while (_pkt_cache.size() > _pkt_cap) {
         _pkt_cache.pop_front();
     }
-    while (timeLatency() > _pkt_latency) {
+    while (timeLatency() > _pkt_latency && TLPKTDrop()) {
         _pkt_cache.pop_front();
     }
     return true;
 }
 
+bool PacketSendQueue::TLPKTDrop(){
+    return (_srt_flag&HSExtMessage::HS_EXT_MSG_TLPKTDROP) && (_srt_flag &HSExtMessage::HS_EXT_MSG_TSBPDSND);
+}
+
 std::list<DataPacket::Ptr> PacketSendQueue::findPacketBySeq(uint32_t start, uint32_t end) {
     std::list<DataPacket::Ptr> re;
     decltype(_pkt_cache.begin()) it;
diff --git a/srt/PacketSendQueue.hpp b/srt/PacketSendQueue.hpp
index be91c663..48bb36b2 100644
--- a/srt/PacketSendQueue.hpp
+++ b/srt/PacketSendQueue.hpp
@@ -16,7 +16,7 @@ public:
     using Ptr = std::shared_ptr<PacketSendQueue>;
     using LostPair = std::pair<uint32_t, uint32_t>;
 
-    PacketSendQueue(uint32_t max_size, uint32_t latency);
+    PacketSendQueue(uint32_t max_size, uint32_t latency,uint32_t flag = 0xbf);
     ~PacketSendQueue() = default;
 
     bool drop(uint32_t num);
@@ -25,7 +25,9 @@ public:
 
 private:
     uint32_t timeLatency();
+    bool TLPKTDrop();
 private:
+    uint32_t _srt_flag;
     uint32_t _pkt_cap;
     uint32_t _pkt_latency;
     std::list<DataPacket::Ptr> _pkt_cache;
diff --git a/srt/SrtTransport.cpp b/srt/SrtTransport.cpp
index 52ecc449..0ef720f2 100644
--- a/srt/SrtTransport.cpp
+++ b/srt/SrtTransport.cpp
@@ -182,9 +182,9 @@ void SrtTransport::handleHandshakeConclusion(HandshakePacket &pkt, struct sockad
         }
         if (req) {
             if (req->srt_flag != srt_flag) {
-                WarnL << " not support flag " << req->srt_flag;
+                WarnL << "  flag " << req->srt_flag;
             }
-            // srt_flag = req->srt_flag;
+            srt_flag = req->srt_flag;
             delay = delay <= req->recv_tsbpd_delay ? req->recv_tsbpd_delay : delay;
         }
         TraceL << getIdentifier() << " CONCLUSION Phase ";
@@ -214,8 +214,8 @@ void SrtTransport::handleHandshakeConclusion(HandshakePacket &pkt, struct sockad
         sendControlPacket(res, true);
         TraceL << " buf size = " << res->max_flow_window_size << " init seq =" << _init_seq_number
                << " latency=" << delay;
-        _recv_buf = std::make_shared<PacketRecvQueue>(getPktBufSize(), _init_seq_number, delay * 1e3);
-        _send_buf = std::make_shared<PacketSendQueue>(getPktBufSize(), delay * 1e3);
+        _recv_buf = std::make_shared<PacketRecvQueue>(getPktBufSize(), _init_seq_number, delay * 1e3,srt_flag);
+        _send_buf = std::make_shared<PacketSendQueue>(getPktBufSize(), delay * 1e3,srt_flag);
         _send_packet_seq_number = _init_seq_number;
         _buf_delay = delay;
         onHandShakeFinished(_stream_id, addr);
@@ -413,6 +413,7 @@ void SrtTransport::sendACKPacket() {
     _last_ack_pkt_seq_num = pkt->last_ack_pkt_seq_number;
     sendControlPacket(pkt, true);
     // TraceL<<"send  ack "<<pkt->dump();
+    // TraceL<<_recv_buf->dump();
 }
 
 void SrtTransport::sendLightACKPacket() {