diff --git a/webrtc/Sdp.cpp b/webrtc/Sdp.cpp
index 757aac80..6f08007e 100644
--- a/webrtc/Sdp.cpp
+++ b/webrtc/Sdp.cpp
@@ -292,7 +292,6 @@ string RtcSessionSdp::toString() const {
 //////////////////////////////////////////////////////////////////////////////////////////
 
 #define SDP_THROW() throw std::invalid_argument(StrPrinter << "解析sdp " << getKey() << " 字段失败:" << str)
-#define SDP_THROW2() throw std::invalid_argument(StrPrinter << "生成sdp " << getKey() << " 字段失败")
 
 void SdpTime::parse(const string &str) {
     if (sscanf(str.data(), "%" SCNu64 " %" SCNu64, &start, &stop) != 2) {
@@ -842,13 +841,7 @@ void RtcSession::loadFrom(const string &str, bool check) {
         }
         rtc_media.rtcp_addr = media.getItemClass<SdpAttrRtcp>('a', "rtcp");
         rtc_media.direction = media.getDirection();
-        {
-            rtc_media.extmap.clear();
-            auto arr = media.getAllItem<SdpAttrExtmap>('a', "extmap");
-            for (auto &ext : arr) {
-                rtc_media.extmap.emplace(ext.id, ext);
-            }
-        }
+        rtc_media.extmap = media.getAllItem<SdpAttrExtmap>('a', "extmap");
         rtc_media.rtcp_mux = media.getItem('a', "rtcp-mux").operator bool();
         rtc_media.rtcp_rsize = media.getItem('a', "rtcp-rsize").operator bool();
 
@@ -1111,8 +1104,8 @@ RtcSessionSdp::Ptr RtcSession::toRtcSessionSdp() const{
         if (m.ice_lite) {
             sdp_media.items.emplace_back(wrapSdpAttr(std::make_shared<SdpCommon>("ice-lite")));
         }
-        for (auto &pr : m.extmap) {
-            sdp_media.items.emplace_back(wrapSdpAttr(std::make_shared<SdpAttrExtmap>(pr.second)));
+        for (auto &ext : m.extmap) {
+            sdp_media.items.emplace_back(wrapSdpAttr(std::make_shared<SdpAttrExtmap>(ext)));
         }
         if (m.direction != RtpDirection::invalid) {
             sdp_media.items.emplace_back(wrapSdpAttr(std::make_shared<DirectionInterfaceImp>(m.direction)));
@@ -1664,9 +1657,9 @@ RETRY:
             }
 
             //对方和我方都支持的扩展，那么我们才支持
-            for (auto &pr : offer_media.extmap) {
-                if (configure.extmap.find(RtpExt::getExtType(pr.second.ext)) != configure.extmap.end()) {
-                    answer_media.extmap.emplace(pr);
+            for (auto &ext : offer_media.extmap) {
+                if (configure.extmap.find(RtpExt::getExtType(ext.ext)) != configure.extmap.end()) {
+                    answer_media.extmap.emplace_back(ext);
                 }
             }
 
diff --git a/webrtc/Sdp.h b/webrtc/Sdp.h
index 3a111649..34c510ef 100644
--- a/webrtc/Sdp.h
+++ b/webrtc/Sdp.h
@@ -633,7 +633,7 @@ public:
     SdpAttrFingerprint fingerprint;
 
     //////// extmap ////////
-    map<uint8_t /*id*/, SdpAttrExtmap> extmap;
+    vector<SdpAttrExtmap> extmap;
 
     //////// sctp ////////////
     SdpAttrSctpMap sctpmap;
diff --git a/webrtc/WebRtcTransport.cpp b/webrtc/WebRtcTransport.cpp
index db01b69c..d7aa1a49 100644
--- a/webrtc/WebRtcTransport.cpp
+++ b/webrtc/WebRtcTransport.cpp
@@ -414,10 +414,10 @@ void WebRtcTransportImp::onStartWebRTC() {
         }
         if (m.type != TrackApplication) {
             //记录rtp ext类型与id的关系，方便接收或发送rtp时修改rtp ext id
-            for (auto &pr : m.extmap) {
-                auto ext_type = RtpExt::getExtType(pr.second.ext);
-                _rtp_ext_id_to_type.emplace(pr.second.id, ext_type);
-                _rtp_ext_type_to_id.emplace(ext_type, pr.second.id);
+            for (auto &ext : m.extmap) {
+                auto ext_type = RtpExt::getExtType(ext.ext);
+                _rtp_ext_id_to_type.emplace(ext.id, ext_type);
+                _rtp_ext_type_to_id.emplace(ext_type, ext.id);
             }
         }
     }