diff --git a/DOC/API/ticket.md b/DOC/API/ticket.md
index 90cf88c..13010a0 100644
--- a/DOC/API/ticket.md
+++ b/DOC/API/ticket.md
@@ -63,10 +63,12 @@ Request:
             "public": true
         },
         "members": {
-            // add a user
-            "525284cc2cebb6d0008b4567": true,
-            // remove a user
-            "4cc2cebb6d5254567280008b": false
+            "add": [
+                "525284cc2cebb6d0008b4567"
+            ],
+            "remove": [
+                "4cc2cebb6d5254567280008b"
+            ]
         }
     }
 
diff --git a/DOC/DEV/Feature/Account.md b/DOC/DEV/Feature/Account.md
index 9b6f5c4..91b9fd2 100644
--- a/DOC/DEV/Feature/Account.md
+++ b/DOC/DEV/Feature/Account.md
@@ -1,5 +1,7 @@
 ## 用户系统
 
+在 API 中，所有需要指明一个用户的参数，都可以使用「用户名」，「邮件地址」，「ID」任意之一。
+
 ### 用户组
 
 * root - 全站最高管理员
diff --git a/core/api/account.coffee b/core/api/account.coffee
index 97e06a3..a49da4f 100644
--- a/core/api/account.coffee
+++ b/core/api/account.coffee
@@ -13,7 +13,7 @@ module.exports =
 
   post:
     signup: (req, res) ->
-      unless /^[0-9a-z_]+$/.test req.body.username
+      unless /^[0-9a-z_]{3,23}$/.test req.body.username
         return res.json 400, error: 'invalid_username'
 
       unless /^\w+([-+.]\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*$/.test req.body.email
@@ -39,7 +39,7 @@ module.exports =
                 id: account._id
 
     login: (req, res) ->
-      mAccount.byUsernameOrEmail req.body.username, (account) ->
+      mAccount.byUsernameOrEmailOrId req.body.username, (account) ->
         unless account
           return res.json 400, error: 'auth_failed'
 
diff --git a/core/api/ticket.coffee b/core/api/ticket.coffee
index a3aad01..4825ff6 100644
--- a/core/api/ticket.coffee
+++ b/core/api/ticket.coffee
@@ -71,7 +71,7 @@ module.exports =
             for memberName in req.body.members
               do (memberName = _.clone(memberName)) ->
                 tasks.push (callback) ->
-                  mAccount.byUsernameOrEmail memberName, (member) ->
+                  mAccount.byUsernameOrEmailOrId memberName, (member) ->
                     unless member
                       res.json 400, error: 'invalid_account', username: memberName
                       callback true
@@ -170,6 +170,37 @@ module.exports =
             else
               return res.json 400, error: 'invalid_status'
 
+          saveToDatabase = ->
+            async.parallel [
+              (callback) ->
+                unless _.isEmpty modifier
+                  mTicket.update _id: ticket._id,
+                    $set: modifier
+                  , {}, callback
+                else
+                  callback()
+
+              (callback) ->
+                unless _.isEmpty addToSetModifier
+                  mTicket.update _id: ticket._id,
+                    $addToSet:
+                      members:
+                        $each: addToSetModifier
+                  , {}, callback
+                else
+                  callback()
+
+              (callback) ->
+                unless _.isEmpty pullModifier
+                  mTicket.update _id: ticket._id,
+                    $pullAll:
+                      members: pullModifier
+                  , {}, callback
+                else
+                  callback()
+            ], ->
+              return res.json {}
+
           if mAccount.inGroup account, 'root'
             if req.body.attribute
               if req.body.attribute.public
@@ -178,42 +209,27 @@ module.exports =
                 modifier['attribute.public'] = false
 
             if req.body.members
-              for member_id, op of req.body.members
-                member_id = db.ObjectID member_id
+              tasks = {}
 
-                if mTicket.getMember ticket, {_id: member_id}
-                  unless op
-                    pullModifier.push member_id
-                else
-                  if op
-                    addToSetModifier.push member_id
+              member_name = _.filter _.union(req.body.members.add, req.body.members.remove), (item) -> item
+              for item in member_name
+                tasks[item] = do (item = _.clone(item)) ->
+                  return (callback) ->
+                    mAccount.byUsernameOrEmailOrId item, (result) ->
+                      callback null, result
 
-          async.parallel [
-            (callback) ->
-              unless _.isEmpty modifier
-                mTicket.update _id: ticket._id,
-                  $set: modifier
-                , {}, callback
-              else
-                callback()
+              async.parallel tasks, (err, result) ->
+                console.log result
 
-            (callback) ->
-              unless _.isEmpty addToSetModifier
-                mTicket.update _id: ticket._id,
-                  $addToSet:
-                    members:
-                      $each: addToSetModifier
-                , {}, callback
-              else
-                callback()
+                if req.body.members.add
+                  for item in req.body.members.add
+                    addToSetModifier.push result[item]._id
 
-            (callback) ->
-              unless _.isEmpty pullModifier
-                mTicket.update _id: ticket._id,
-                  $pullAll:
-                    members: pullModifier
-                , {}, callback
-              else
-                callback()
-          ], ->
-            return res.json {}
+                if req.body.members.remove
+                  for item in req.body.members.remove
+                    pullModifier.push result[item]._id
+
+                saveToDatabase()
+
+          else
+            saveToDatabase()
diff --git a/core/model/account.coffee b/core/model/account.coffee
index cdb0d9a..f59a1d8 100644
--- a/core/model/account.coffee
+++ b/core/model/account.coffee
@@ -79,12 +79,16 @@ exports.authenticate = (token, callback) ->
     'tokens.token': token
   , {}, callback
 
-exports.byUsernameOrEmail = (username, callback) ->
+exports.byUsernameOrEmailOrId = (username, callback) ->
   exports.byUsername username, (account) ->
     if account
       return callback account
 
-    exports.byEmail username, callback
+    exports.byEmail username, (account) ->
+      if account
+        return callback account
+
+      exports.findId username, callback
 
 # @return bool
 exports.matchPasswd = (account, passwd) ->