diff --git a/Yep/Realm/Models.swift b/Yep/Realm/Models.swift
index cb576cf6..7ff679e8 100644
--- a/Yep/Realm/Models.swift
+++ b/Yep/Realm/Models.swift
@@ -259,6 +259,11 @@ func groupWithGroupID(groupID: String, inRealm realm: Realm) -> Group? {
     return realm.objects(Group).filter(predicate).first
 }
 
+func countOfUnreadMessagesInRealm(realm: Realm) -> Int {
+    let predicate = NSPredicate(format: "readed = false AND fromFriend.friendState != %d", UserFriendState.Me.rawValue)
+    return realm.objects(Message).filter(predicate).count
+}
+
 func messageWithMessageID(messageID: String, inRealm realm: Realm) -> Message? {
     if messageID.isEmpty {
         return nil
diff --git a/Yep/ViewControllers/Conversation/ConversationViewController.swift b/Yep/ViewControllers/Conversation/ConversationViewController.swift
index d0692e13..c09c2bf5 100644
--- a/Yep/ViewControllers/Conversation/ConversationViewController.swift
+++ b/Yep/ViewControllers/Conversation/ConversationViewController.swift
@@ -1147,16 +1147,19 @@ extension ConversationViewController: UICollectionViewDataSource, UICollectionVi
                 // TODO: 需要更好的下载与 mark as read 逻辑：也许未下载的也可以 mark as read
                 downloadAttachmentOfMessage(message)
 
-                markAsReadMessage(message, failureHandler: nil) { success in
-                    dispatch_async(dispatch_get_main_queue()) {
-                        let realm = Realm()
-                        
-                        if let message = messageWithMessageID(message.messageID, inRealm: realm) {
-                            realm.write {
-                                message.readed = true
-                            }
+                // 防止未在此界面时被标记
+                if navigationController?.topViewController == self {
+                    markAsReadMessage(message, failureHandler: nil) { success in
+                        dispatch_async(dispatch_get_main_queue()) {
+                            let realm = Realm()
 
-                            println("\(message.messageID) mark as read")
+                            if let message = messageWithMessageID(message.messageID, inRealm: realm) {
+                                realm.write {
+                                    message.readed = true
+                                }
+
+                                println("\(message.messageID) mark as read")
+                            }
                         }
                     }
                 }
diff --git a/Yep/ViewControllers/Conversations/ConversationsViewController.swift b/Yep/ViewControllers/Conversations/ConversationsViewController.swift
index c6f3af72..0c50834e 100644
--- a/Yep/ViewControllers/Conversations/ConversationsViewController.swift
+++ b/Yep/ViewControllers/Conversations/ConversationsViewController.swift
@@ -17,6 +17,22 @@ class ConversationsViewController: UIViewController {
 
     var realm: Realm!
 
+    var unreadMessagesToken: NotificationToken?
+    var haveUnreadMessages = false {
+        didSet {
+            if haveUnreadMessages != oldValue {
+                if haveUnreadMessages {
+                    navigationController?.tabBarItem.image = UIImage(named: "icon_chat_unread")
+                    navigationController?.tabBarItem.selectedImage = UIImage(named: "icon_chat_active_unread")
+
+                } else {
+                    navigationController?.tabBarItem.image = UIImage(named: "icon_chat")
+                    navigationController?.tabBarItem.selectedImage = UIImage(named: "icon_chat_active")
+                }
+            }
+        }
+    }
+
     lazy var conversations: Results<Conversation> = {
         return self.realm.objects(Conversation).sorted("updatedAt", ascending: false)
         }()
@@ -47,8 +63,9 @@ class ConversationsViewController: UIViewController {
         conversationsTableView.registerNib(UINib(nibName: cellIdentifier, bundle: nil), forCellReuseIdentifier: cellIdentifier)
         conversationsTableView.rowHeight = 80
 
-        navigationController?.tabBarItem.image = UIImage(named: "icon_chat_unread")
-        navigationController?.tabBarItem.selectedImage = UIImage(named: "icon_chat_active_unread")
+        unreadMessagesToken = realm.addNotificationBlock { notification, realm in
+            self.haveUnreadMessages = countOfUnreadMessagesInRealm(realm) > 0
+        }
     }
 
     override func viewDidAppear(animated: Bool) {