diff --git a/Realtime/Conversation/LCIMConversation.cs b/Realtime/Conversation/LCIMConversation.cs
index 26c4f3e..8f19470 100644
--- a/Realtime/Conversation/LCIMConversation.cs
+++ b/Realtime/Conversation/LCIMConversation.cs
@@ -61,10 +61,28 @@ namespace LeanCloud.Realtime {
             get; internal set;
         }
 
-        public DateTime LastMessageAt {
+        public long LastDeliveredTimestamp {
             get; internal set;
         }
 
+        public DateTime LastDeliveredAt {
+            get {
+                DateTimeOffset dateTimeOffset = DateTimeOffset.FromUnixTimeMilliseconds(LastDeliveredTimestamp);
+                return dateTimeOffset.DateTime;
+            }
+        }
+
+        public long LastReadTimestamp {
+            get; internal set;
+        }
+
+        public DateTime LastReadAt {
+            get {
+                DateTimeOffset dateTimeOffset = DateTimeOffset.FromUnixTimeMilliseconds(LastReadTimestamp);
+                return dateTimeOffset.DateTime;
+            }
+        }
+
         public object this[string key] {
             get {
                 return customProperties[key];
@@ -243,6 +261,11 @@ namespace LeanCloud.Realtime {
             return await Client.ConversationController.BlockMembers(Id, clientIds);
         }
 
+        /// <summary>
+        /// 将用户移除黑名单
+        /// </summary>
+        /// <param name="clientIds"></param>
+        /// <returns></returns>
         public async Task<LCIMPartiallySuccessResult> UnblockMembers(IEnumerable<string> clientIds) {
             if (clientIds == null || clientIds.Count() == 0) {
                 throw new ArgumentNullException(nameof(clientIds));
@@ -334,14 +357,23 @@ namespace LeanCloud.Realtime {
         /// <summary>
         /// 查询黑名单用户
         /// </summary>
-        /// <param name="limit"></param>
-        /// <param name="next"></param>
+        /// <param name="limit">限制</param>
+        /// <param name="next">其实用户 Id</param>
         /// <returns></returns>
         public async Task<LCIMPageResult> QueryBlockedMembers(int limit = 10,
             string next = null) {
             return await Client.ConversationController.QueryBlockedMembers(Id, limit, next);
         }
 
+        /// <summary>
+        /// 查询聊天记录
+        /// </summary>
+        /// <param name="start">起点</param>
+        /// <param name="end">终点</param>
+        /// <param name="direction">查找方向</param>
+        /// <param name="limit">限制</param>
+        /// <param name="messageType">消息类型</param>
+        /// <returns></returns>
         public async Task<List<LCIMMessage>> QueryMessages(LCIMMessageQueryEndpoint start = null,
             LCIMMessageQueryEndpoint end = null,
             LCIMMessageQueryDirection direction = LCIMMessageQueryDirection.NewToOld,
@@ -350,6 +382,14 @@ namespace LeanCloud.Realtime {
             return await Client.MessageController.QueryMessages(Id, start, end, direction, limit, messageType);
         }
 
+        /// <summary>
+        /// 获取会话已收/已读时间戳
+        /// </summary>
+        /// <returns></returns>
+        public async Task FetchReciptTimestamps() {
+            await Client.ConversationController.FetchReciptTimestamp(Id);
+        }
+
         internal static bool IsTemporayConversation(string convId) {
             return convId.StartsWith("_tmp:");
         }
@@ -381,9 +421,9 @@ namespace LeanCloud.Realtime {
                 IEnumerable<string> ids = (muo as IList<object>).Cast<string>();
                 mutedIds = new HashSet<string>(ids);
             }
-            if (conv.TryGetValue("lm", out object lmo)) {
-                LastMessageAt = (DateTime)LCDecoder.Decode(lmo);
-            }
+            //if (conv.TryGetValue("lm", out object lmo)) {
+            //    LastMessageAt = (DateTime)LCDecoder.Decode(lmo);
+            //}
         }
 
         internal void MergeInfo(Dictionary<string, object> attr) {
diff --git a/Realtime/Internal/Controller/LCIMConversationController.cs b/Realtime/Internal/Controller/LCIMConversationController.cs
index 12749a9..122bb53 100644
--- a/Realtime/Internal/Controller/LCIMConversationController.cs
+++ b/Realtime/Internal/Controller/LCIMConversationController.cs
@@ -498,6 +498,19 @@ namespace LeanCloud.Realtime.Internal.Controller {
             return convList;
         }
 
+        internal async Task FetchReciptTimestamp(string convId) {
+            ConvCommand convCommand = new ConvCommand {
+                Cid = convId
+            };
+            GenericCommand request = Client.NewCommand(CommandType.Conv, OpType.MaxRead);
+            request.ConvMessage = convCommand;
+            GenericCommand response = await Connection.SendRequest(request);
+            convCommand = response.ConvMessage;
+            LCIMConversation conversation = await Client.GetOrQueryConversation(convCommand.Cid);
+            conversation.LastDeliveredTimestamp = convCommand.MaxAckTimestamp;
+            conversation.LastReadTimestamp = convCommand.MaxReadTimestamp;
+        }
+
         private LCIMPartiallySuccessResult NewPartiallySuccessResult(IEnumerable<string> succesfulIds,
             IEnumerable<ErrorCommand> errors) {
             LCIMPartiallySuccessResult result = new LCIMPartiallySuccessResult {