diff --git a/src/Rtcp/RtcpFCI.cpp b/src/Rtcp/RtcpFCI.cpp
index 67d82ca8..dd7f2457 100644
--- a/src/Rtcp/RtcpFCI.cpp
+++ b/src/Rtcp/RtcpFCI.cpp
@@ -183,7 +183,7 @@ vector<bool> FCI_NACK::getBitArray() const {
     vector<bool> ret;
     ret.resize(kBitSize + 1);
     //nack第一个包丢包
-    ret[0] = false;
+    ret[0] = true;
 
     auto blp_h = getBlp();
     for (size_t i = 0; i < kBitSize; ++i) {
diff --git a/src/Rtcp/RtcpFCI.h b/src/Rtcp/RtcpFCI.h
index a3d5e96e..1b68e457 100644
--- a/src/Rtcp/RtcpFCI.h
+++ b/src/Rtcp/RtcpFCI.h
@@ -243,18 +243,17 @@ private:
 class FCI_NACK {
 public:
     static constexpr size_t kSize = 4;
+    static constexpr size_t kBitSize = 16;
 
     FCI_NACK(uint16_t pid_h, const vector<bool> &type);
 
     void check(size_t size);
     uint16_t getPid() const;
     uint16_t getBlp() const;
+    //返回丢包列表，总长度17，第一个包必丢
     vector<bool> getBitArray() const;
     string dumpString() const;
 
-private:
-    static constexpr size_t kBitSize = 16;
-
 private:
     // The PID field is used to specify a lost packet.  The PID field
     //      refers to the RTP sequence number of the lost packet.
diff --git a/src/Rtsp/RtpReceiver.h b/src/Rtsp/RtpReceiver.h
index a5f1eaa0..24cf8fb8 100644
--- a/src/Rtsp/RtpReceiver.h
+++ b/src/Rtsp/RtpReceiver.h
@@ -21,7 +21,7 @@ using namespace toolkit;
 
 namespace mediakit {
 
-template<typename T, typename SEQ = uint16_t, size_t kMax = 256, size_t kMin = 10>
+template<typename T, typename SEQ = uint16_t, size_t kMax = 1024, size_t kMin = 32>
 class PacketSortor {
 public:
     PacketSortor() = default;
diff --git a/tests/test_rtcp_nack.cpp b/tests/test_rtcp_nack.cpp
new file mode 100644
index 00000000..7463ce02
--- /dev/null
+++ b/tests/test_rtcp_nack.cpp
@@ -0,0 +1,37 @@
+/*
+ * Copyright (c) 2016 The ZLToolKit project authors. All Rights Reserved.
+ *
+ * This file is part of ZLToolKit(https://github.com/xia-chu/ZLToolKit).
+ *
+ * Use of this source code is governed by MIT license that can be found in the
+ * LICENSE file in the root of the source tree. All contributing project authors
+ * may be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include <iostream>
+#include "Util/logger.h"
+#include "Rtcp/RtcpFCI.h"
+#include "../webrtc/WebRtcTransport.h"
+using namespace std;
+using namespace toolkit;
+using namespace mediakit;
+
+extern void testFCI();
+
+int main() {
+    Logger::Instance().add(std::make_shared<ConsoleChannel>());
+
+    srand((unsigned) time(NULL));
+
+    NackContext ctx;
+    for (int i = 1; i < 1000; ++i) {
+        if (i % (1 + (rand() % 30)) == 0) {
+            DebugL << "drop:" << i;
+        } else {
+            ctx.received(i);
+
+        }
+    }
+    sleep(1);
+    return 0;
+}
diff --git a/webrtc/WebRtcTransport.cpp b/webrtc/WebRtcTransport.cpp
index f06a20be..1cd574c8 100644
--- a/webrtc/WebRtcTransport.cpp
+++ b/webrtc/WebRtcTransport.cpp
@@ -424,9 +424,9 @@ void WebRtcTransportImp::onStartWebRTC() {
             }
             ref.rtcp_context_recv = std::make_shared<RtcpContext>(ref.plan->sample_rate, true);
             ref.rtcp_context_send = std::make_shared<RtcpContext>(ref.plan->sample_rate, false);
-            ref.receiver = std::make_shared<RtpReceiverImp>([&ref, this](RtpPacket::Ptr rtp) {
+            ref.receiver = std::make_shared<RtpReceiverImp>([&ref, this](RtpPacket::Ptr rtp) mutable{
                 onSortedRtp(ref, std::move(rtp));
-            }, [&ref, this](const RtpPacket::Ptr &rtp) {
+            }, [&ref, this](const RtpPacket::Ptr &rtp) mutable {
                 onBeforeSortedRtp(ref, rtp);
             });
         }
@@ -674,15 +674,28 @@ void WebRtcTransportImp::onRtp(const char *buf, size_t len) {
         return;
     }
     auto &info = it->second;
+
+#if 1
+    //此处模拟接受丢包
+    auto header = (RtpHeader *) buf;
+    auto seq = ntohs(header->seq);
+    if (seq % 10 == 0) {
+        //丢包
+        return;
+    } else {
+        info.nack_ctx.received(seq);
+    }
+#endif
+
     //解析并排序rtp
     info.receiver->inputRtp(info.media->type, info.plan->sample_rate, (uint8_t *) buf, len);
 }
 
 ///////////////////////////////////////////////////////////////////
 
-void WebRtcTransportImp::onSortedRtp(const RtpPayloadInfo &info, RtpPacket::Ptr rtp) {
-    if(!info.is_common_rtp){
-        //todo rtx/red/ulpfec类型的rtp先未处理
+void WebRtcTransportImp::onSortedRtp(RtpPayloadInfo &info, RtpPacket::Ptr rtp) {
+    if (!info.is_common_rtp) {
+        WarnL;
         return;
     }
     if (info.media->type == TrackVideo && _pli_ticker.elapsedTime() > 2000) {
@@ -724,7 +737,7 @@ static void changeRtpExtId(const RtpHeader *header, const Type &map) {
     }
 }
 
-void WebRtcTransportImp::onBeforeSortedRtp(const RtpPayloadInfo &info, const RtpPacket::Ptr &rtp) {
+void WebRtcTransportImp::onBeforeSortedRtp(RtpPayloadInfo &info, const RtpPacket::Ptr &rtp) {
     changeRtpExtId(rtp->getHeader(), _rtp_ext_id_to_type);
     //统计rtp收到的情况，好做rr汇报
     info.rtcp_context_recv->onRtp(rtp->getSeq(), rtp->getStampMS(), rtp->size() - RtpPacket::kRtpTcpHeaderSize);
@@ -740,6 +753,12 @@ void WebRtcTransportImp::onSendRtp(const RtpPacket::Ptr &rtp, bool flush, bool r
         //统计rtp发送情况，好做sr汇报
         info->rtcp_context_send->onRtp(rtp->getSeq(), rtp->getStampMS(), rtp->size() - RtpPacket::kRtpTcpHeaderSize);
         info->nack_list.push_back(rtp);
+#if 0
+        //此处模拟发送丢包
+        if(rtp->getSeq() % 10 == 0){
+            return;
+        }
+#endif
     } else {
         WarnL << "重传rtp:" << rtp->getSeq();
     }
diff --git a/webrtc/WebRtcTransport.h b/webrtc/WebRtcTransport.h
index 7b911020..caeb80a6 100644
--- a/webrtc/WebRtcTransport.h
+++ b/webrtc/WebRtcTransport.h
@@ -131,8 +131,8 @@ class NackList {
 public:
     void push_back(RtpPacket::Ptr rtp) {
         auto seq = rtp->getSeq();
-        nack_cache_seq.emplace_back(seq);
-        nack_cache_pkt.emplace(seq, std::move(rtp));
+        _nack_cache_seq.emplace_back(seq);
+        _nack_cache_pkt.emplace(seq, std::move(rtp));
         while (get_cache_ms() > kMaxNackMS) {
             //需要清除部分nack缓存
             pop_front();
@@ -143,7 +143,7 @@ public:
     void for_each_nack(const FCI_NACK &nack, const FUNC &func) {
         auto seq = nack.getPid();
         for (auto bit : nack.getBitArray()) {
-            if (!bit) {
+            if (bit) {
                 //丢包
                 RtpPacket::Ptr *ptr = get_rtp(seq);
                 if (ptr) {
@@ -156,27 +156,27 @@ public:
 
 private:
     void pop_front() {
-        if (nack_cache_seq.empty()) {
+        if (_nack_cache_seq.empty()) {
             return;
         }
-        nack_cache_pkt.erase(nack_cache_seq.front());
-        nack_cache_seq.pop_front();
+        _nack_cache_pkt.erase(_nack_cache_seq.front());
+        _nack_cache_seq.pop_front();
     }
 
     RtpPacket::Ptr *get_rtp(uint16_t seq) {
-        auto it = nack_cache_pkt.find(seq);
-        if (it == nack_cache_pkt.end()) {
+        auto it = _nack_cache_pkt.find(seq);
+        if (it == _nack_cache_pkt.end()) {
             return nullptr;
         }
         return &it->second;
     }
 
     uint32_t get_cache_ms() {
-        if (nack_cache_seq.size() < 2) {
+        if (_nack_cache_seq.size() < 2) {
             return 0;
         }
-        uint32_t back = nack_cache_pkt[nack_cache_seq.back()]->getStampMS();
-        uint32_t front = nack_cache_pkt[nack_cache_seq.front()]->getStampMS();
+        uint32_t back = _nack_cache_pkt[_nack_cache_seq.back()]->getStampMS();
+        uint32_t front = _nack_cache_pkt[_nack_cache_seq.front()]->getStampMS();
         if (back > front) {
             return back - front;
         }
@@ -186,8 +186,81 @@ private:
 
 private:
     static constexpr uint32_t kMaxNackMS = 10 * 1000;
-    deque<uint16_t> nack_cache_seq;
-    unordered_map<uint16_t, RtpPacket::Ptr > nack_cache_pkt;
+    deque<uint16_t> _nack_cache_seq;
+    unordered_map<uint16_t, RtpPacket::Ptr > _nack_cache_pkt;
+};
+
+class NackContext {
+public:
+    void received(uint16_t seq) {
+        if (!_last_max_seq && _seq.empty()) {
+            _last_max_seq = seq - 1;
+        }
+        _seq.emplace(seq);
+        auto max_seq = *_seq.rbegin();
+        auto min_seq = *_seq.begin();
+        auto diff = max_seq - min_seq;
+        if (!diff) {
+            return;
+        }
+
+        if (diff > UINT32_MAX / 2) {
+            //回环
+            _seq.clear();
+            _last_max_seq = min_seq;
+            return;
+        }
+
+        if (_seq.size() == diff + 1 && _last_max_seq + 1 == min_seq) {
+            //都是连续的seq，未丢包
+            _seq.clear();
+            _last_max_seq = max_seq;
+        } else {
+            //seq不连续，有丢包
+            if (min_seq == _last_max_seq + 1) {
+                //前面部分seq是连续的，未丢包，移除之
+                eraseFrontSeq();
+            }
+
+            //有丢包，丢包从_last_max_seq开始
+            if (max_seq - _last_max_seq > FCI_NACK::kBitSize) {
+                vector<bool> vec;
+                vec.resize(FCI_NACK::kBitSize);
+                for (auto i = 0; i < FCI_NACK::kBitSize; ++i) {
+                    vec[i] = _seq.find(_last_max_seq + i + 2) == _seq.end();
+                }
+                onNack(FCI_NACK(_last_max_seq + 1, vec));
+                _last_max_seq += FCI_NACK::kBitSize + 1;
+                if (_last_max_seq >= max_seq) {
+                    _seq.clear();
+                } else {
+                    auto it = _seq.emplace_hint(_seq.begin(), _last_max_seq);
+                    _seq.erase(_seq.begin(), it);
+                }
+            }
+        }
+    }
+
+    void onNack(const FCI_NACK &nack) {
+        InfoL << nack.dumpString() << " " << _seq.size();
+    }
+
+private:
+    void eraseFrontSeq(){
+        //前面部分seq是连续的，未丢包，移除之
+        for (auto it = _seq.begin(); it != _seq.end();) {
+            if (*it != _last_max_seq + 1) {
+                //seq不连续，丢包了
+                break;
+            }
+            _last_max_seq = *it;
+            it = _seq.erase(it);
+        }
+    }
+
+private:
+    set<uint16_t> _seq;
+    uint16_t _last_max_seq = 0;
 };
 
 class WebRtcTransportImp : public WebRtcTransport, public MediaSourceEvent, public SockInfo, public std::enable_shared_from_this<WebRtcTransportImp>{
@@ -265,10 +338,11 @@ private:
         RtcpContext::Ptr rtcp_context_recv;
         RtcpContext::Ptr rtcp_context_send;
         NackList nack_list;
+        NackContext nack_ctx;
     };
 
-    void onSortedRtp(const RtpPayloadInfo &info, RtpPacket::Ptr rtp);
-    void onBeforeSortedRtp(const RtpPayloadInfo &info, const RtpPacket::Ptr &rtp);
+    void onSortedRtp(RtpPayloadInfo &info, RtpPacket::Ptr rtp);
+    void onBeforeSortedRtp(RtpPayloadInfo &info, const RtpPacket::Ptr &rtp);
 
 private:
     //用掉的总流量