diff --git a/Realtime/Realtime/Internal/Connection/LCConnection.cs b/Realtime/Realtime/Internal/Connection/LCConnection.cs
index c4703fa..1e7732a 100644
--- a/Realtime/Realtime/Internal/Connection/LCConnection.cs
+++ b/Realtime/Realtime/Internal/Connection/LCConnection.cs
@@ -1,4 +1,5 @@
 using System;
+using System.Linq;
 using System.Text;
 using System.Collections.Generic;
 using System.Threading.Tasks;
@@ -12,6 +13,17 @@ namespace LeanCloud.Realtime.Internal.Connection {
     /// 连接层，只与数据协议相关
     /// </summary>
     public class LCConnection {
+        // 请求/应答比对，即 I 相等
+        class RequestAndResponseComparer : IEqualityComparer<GenericCommand> {
+            public bool Equals(GenericCommand x, GenericCommand y) {
+                return true;
+            }
+
+            public int GetHashCode(GenericCommand obj) {
+                return obj.I;
+            }
+        }
+
         /// <summary>
         /// 连接状态
         /// </summary>
@@ -59,8 +71,7 @@ namespace LeanCloud.Realtime.Internal.Connection {
         /// <summary>
         /// 请求回调缓存
         /// </summary>
-        private readonly Dictionary<int, TaskCompletionSource<GenericCommand>> responses;
-        private readonly List<GenericCommand> sendingRequests;
+        private readonly Dictionary<GenericCommand, TaskCompletionSource<GenericCommand>> requestToResponses;
 
         private int requestI = 1;
 
@@ -79,8 +90,8 @@ namespace LeanCloud.Realtime.Internal.Connection {
 
         internal LCConnection(string id) {
             this.id = id;
-            responses = new Dictionary<int, TaskCompletionSource<GenericCommand>>();
-            sendingRequests = new List<GenericCommand>();
+            requestToResponses = new Dictionary<GenericCommand, TaskCompletionSource<GenericCommand>>(new RequestAndResponseComparer());
+
             heartBeat = new LCHeartBeat(this, OnDisconnect);
             router = new LCRTMRouter();
             ws = new LCWebSocketClient {
@@ -130,25 +141,23 @@ namespace LeanCloud.Realtime.Internal.Connection {
         /// <returns></returns>
         internal async Task<GenericCommand> SendRequest(GenericCommand request) {
             if (IsIdempotentCommand(request)) {
-                GenericCommand sendingReq = sendingRequests.Find(item => {
+                GenericCommand sendingReq = requestToResponses.Keys.FirstOrDefault(item => {
                     // TRICK 除了 I 其他字段相等
                     request.I = item.I;
                     return Equals(request, item);
                 });
                 if (sendingReq != null) {
                     LCLogger.Warn("duplicated request");
-                    if (responses.TryGetValue(sendingReq.I, out TaskCompletionSource<GenericCommand> waitingTcs)) {
+                    if (requestToResponses.TryGetValue(sendingReq, out TaskCompletionSource<GenericCommand> waitingTcs)) {
                         return await waitingTcs.Task;
                     }
                     LCLogger.Error($"error request: {request}");
-                } else {
-                    sendingRequests.Add(request);
                 }
             }
 
             TaskCompletionSource<GenericCommand> tcs = new TaskCompletionSource<GenericCommand>();
             request.I = requestI++;
-            responses.Add(request.I, tcs);
+            requestToResponses.Add(request, tcs);
             try {
                 await SendCommand(request);
             } catch (Exception e) {
@@ -196,7 +205,7 @@ namespace LeanCloud.Realtime.Internal.Connection {
                 if (command.HasI) {
                     // 应答
                     int requestIndex = command.I;
-                    if (responses.TryGetValue(requestIndex, out TaskCompletionSource<GenericCommand> tcs)) {
+                    if (requestToResponses.TryGetValue(command, out TaskCompletionSource<GenericCommand> tcs)) {
                         if (command.HasErrorMessage) {
                             // 错误
                             ErrorCommand error = command.ErrorMessage;
@@ -206,12 +215,9 @@ namespace LeanCloud.Realtime.Internal.Connection {
                             LCException exception = new LCException(code, detail);
                             tcs.TrySetException(exception);
                         } else {
-                            sendingRequests.RemoveAll(item => {
-                                return item.I == command.I;
-                            });
                             tcs.TrySetResult(command);
                         }
-                        responses.Remove(requestIndex);
+                        requestToResponses.Remove(command);
                     } else {
                         LCLogger.Error($"No request for {requestIndex}");
                     }