diff --git a/src/Application.hpp b/src/Application.hpp
index 3e8f104..d7b7cc9 100644
--- a/src/Application.hpp
+++ b/src/Application.hpp
@@ -57,8 +57,8 @@ class Application {
         LogError("argument method is illegal.");
     }
   }
-  void insertUserWord(const string& word, const string& tag = UNKNOWN_TAG) {
-    dictTrie_.insertUserWord(word, tag);
+  bool insertUserWord(const string& word, const string& tag = UNKNOWN_TAG) {
+    return dictTrie_.insertUserWord(word, tag);
   }
   void tag(const string& str, vector<pair<string, string> >& res) const {
     tagger_.tag(str, res);
diff --git a/src/DictTrie.hpp b/src/DictTrie.hpp
index 0f02f4f..4fdd478 100644
--- a/src/DictTrie.hpp
+++ b/src/DictTrie.hpp
@@ -13,8 +13,6 @@
 #include "TransCode.hpp"
 #include "Trie.hpp"
 
-
-
 namespace CppJieba {
 using namespace Limonp;
 const double MIN_DOUBLE = -3.14e+100;
@@ -44,16 +42,25 @@ class DictTrie {
       LogFatal("trie already initted");
     }
     loadDict_(dictPath);
-    calculateWeight_(nodeInfos_);
-    minWeight_ = findMinWeight_(nodeInfos_);
-    maxWeight_ = findMaxWeight_(nodeInfos_);
+    calculateWeight_(staticNodeInfos_);
+    minWeight_ = findMinWeight_(staticNodeInfos_);
+    maxWeight_ = findMaxWeight_(staticNodeInfos_);
 
     if(userDictPath.size()) {
       loadUserDict_(userDictPath);
     }
-    shrink_(nodeInfos_);
-    trie_ = createTrie_(nodeInfos_);
-    assert(trie_);
+    shrink_(staticNodeInfos_);
+    createTrie_(staticNodeInfos_);
+  }
+  
+  bool insertUserWord(const string& word, const string& tag = UNKNOWN_TAG) {
+    DictUnit nodeInfo;
+    if(!makeUserNodeInfo_(nodeInfo, word, tag)) {
+      return false;
+    }
+    activeNodeInfos_.push_back(nodeInfo);
+    trie_->insertNode(nodeInfo.word, &activeNodeInfos_.back());
+    return true;
   }
 
   const DictUnit* find(Unicode::const_iterator begin, Unicode::const_iterator end) const {
@@ -67,20 +74,6 @@ class DictTrie {
     vector<SegmentChar>& res) const {
     trie_->find(begin, end, res);
   }
-  bool insertUserWord(const string& word, const string& tag = UNKNOWN_TAG) {
-    DictUnit nodeInfo;
-    if(!TransCode::decode(word, nodeInfo.word)) {
-      LogError("decode %s failed.", word.c_str());
-      return false;
-    }
-    if(nodeInfo.word.size() == 1) {
-      userDictSingleChineseWord_.insert(nodeInfo.word[0]);
-    }
-    nodeInfo.weight = maxWeight_;
-    nodeInfo.tag = tag;
-    nodeInfos_.push_back(nodeInfo);
-    return true;
-  } 
   bool isUserDictSingleChineseWord(const Unicode::value_type& word) const {
     return isIn(userDictSingleChineseWord_, word);
   }
@@ -88,9 +81,8 @@ class DictTrie {
     return minWeight_;
   };
 
-
  private:
-  Trie * createTrie_(const vector<DictUnit>& dictUnits) {
+  void createTrie_(const vector<DictUnit>& dictUnits) {
     assert(dictUnits.size());
     vector<Unicode> words;
     vector<const DictUnit*> valuePointers;
@@ -99,8 +91,7 @@ class DictTrie {
       valuePointers.push_back(&dictUnits[i]);
     }
 
-    Trie * trie = new Trie(words, valuePointers);
-    return trie;
+    trie_ = new Trie(words, valuePointers);
   }
   void loadUserDict_(const string& filePath) {
     ifstream ifs(filePath.c_str());
@@ -117,19 +108,37 @@ class DictTrie {
       if(buf.size() < 1) {
         LogFatal("split [%s] result illegal", line.c_str());
       }
-      insertUserWord(buf[0], (buf.size() == 2 ? buf[1] : UNKNOWN_TAG));
+      DictUnit nodeInfo;
+      makeUserNodeInfo_(nodeInfo, buf[0], 
+            (buf.size() == 2 ? buf[1] : UNKNOWN_TAG));
+      staticNodeInfos_.push_back(nodeInfo);
     }
     LogInfo("load userdict[%s] ok. lines[%u]", filePath.c_str(), lineno);
   }
-  bool insertWord_(const string& word, double weight, const string& tag) {
-    DictUnit nodeInfo;
+  bool makeNodeInfo(DictUnit& nodeInfo,
+        const string& word, 
+        double weight, 
+        const string& tag) {
     if(!TransCode::decode(word, nodeInfo.word)) {
       LogError("decode %s failed.", word.c_str());
       return false;
     }
     nodeInfo.weight = weight;
     nodeInfo.tag = tag;
-    nodeInfos_.push_back(nodeInfo);
+    return true;
+  }
+  bool makeUserNodeInfo_(DictUnit& nodeInfo, 
+        const string& word, 
+        const string& tag = UNKNOWN_TAG) {
+    if(!TransCode::decode(word, nodeInfo.word)) {
+      LogError("decode %s failed.", word.c_str());
+      return false;
+    }
+    if(nodeInfo.word.size() == 1) {
+      userDictSingleChineseWord_.insert(nodeInfo.word[0]);
+    }
+    nodeInfo.weight = maxWeight_;
+    nodeInfo.tag = tag;
     return true;
   }
   void loadDict_(const string& filePath) {
@@ -146,7 +155,11 @@ class DictTrie {
       if(buf.size() != DICT_COLUMN_NUM) {
         LogFatal("split result illegal, line: %s, result size: %u", line.c_str(), buf.size());
       }
-      insertWord_(buf[0], atof(buf[1].c_str()), buf[2]);
+      makeNodeInfo(nodeInfo, 
+            buf[0], 
+            atof(buf[1].c_str()), 
+            buf[2]);
+      staticNodeInfos_.push_back(nodeInfo);
     }
   }
   double findMinWeight_(const vector<DictUnit>& nodeInfos) const {
@@ -182,7 +195,8 @@ class DictTrie {
   }
 
  private:
-  vector<DictUnit> nodeInfos_;
+  vector<DictUnit> staticNodeInfos_;
+  deque<DictUnit> activeNodeInfos_; // must not be vector
   Trie * trie_;
 
   double minWeight_;
diff --git a/src/Trie.hpp b/src/Trie.hpp
index 7363d10..cfc20e3 100644
--- a/src/Trie.hpp
+++ b/src/Trie.hpp
@@ -85,13 +85,11 @@ class Trie {
     return ptNode->ptValue;
   }
   // aho-corasick-automation
-  void find(
-    Unicode::const_iterator begin,
+  void find(Unicode::const_iterator begin,
     Unicode::const_iterator end,
-    vector<struct SegmentChar>& res
-  ) const {
+    vector<struct SegmentChar>& res) const {
     res.resize(end - begin);
-    const TrieNode * now = root_;
+    const TrieNode* now = root_;
     const TrieNode* node;
     // compiler will complain warnings if only "i < end - begin" .
     for (size_t i = 0; i < size_t(end - begin); i++) {
@@ -134,8 +132,7 @@ class Trie {
       }
     }
   }
-  bool find(
-    Unicode::const_iterator begin,
+  bool find(Unicode::const_iterator begin,
     Unicode::const_iterator end,
     DagType & res,
     size_t offset = 0) const {
@@ -157,6 +154,9 @@ class Trie {
     }
     return !res.empty();
   }
+  void insertNode(const Unicode& key, const DictUnit* ptValue) {
+    insertNode_(key, ptValue);
+  }
  private:
   void build_() {
     queue<TrieNode*> que;
@@ -191,7 +191,8 @@ class Trie {
       }
     }
   }
-  void createTrie_(const vector<Unicode>& keys, const vector<const DictUnit*> & valuePointers) {
+  void createTrie_(const vector<Unicode>& keys, 
+        const vector<const DictUnit*> & valuePointers) {
     if(valuePointers.empty() || keys.empty()) {
       return;
     }
diff --git a/test/unittest/TApplication.cpp b/test/unittest/TApplication.cpp
index 3023a51..bfb888a 100644
--- a/test/unittest/TApplication.cpp
+++ b/test/unittest/TApplication.cpp
@@ -51,10 +51,22 @@ TEST(ApplicationTest, Test1) {
   ASSERT_EQ(result, "[\"CEO:11.7392\", \"升职:10.8562\", \"加薪:10.6426\", \"手扶拖拉机:10.0089\", \"巅峰:9.49396\"]");
 }
 
-//TEST(ApplicationTest, InsertUserWord) {
-//  CppJieba::Application app("../dict/jieba.dict.utf8",
-//                            "../dict/hmm_model.utf8",
-//                            "../dict/user.dict.utf8",
-//                            "../dict/idf.utf8",
-//                            "../dict/stop_words.utf8");
-//}
+TEST(ApplicationTest, InsertUserWord) {
+  CppJieba::Application app("../dict/jieba.dict.utf8",
+                            "../dict/hmm_model.utf8",
+                            "../dict/user.dict.utf8",
+                            "../dict/idf.utf8",
+                            "../dict/stop_words.utf8");
+  vector<string> words;
+  string result;
+
+  app.cut("男默女泪", words);
+  result << words;
+  ASSERT_EQ("[\"男默\", \"女泪\"]", result);
+
+  //ASSERT_TRUE(app.insertUserWord("男默女泪"));
+
+  //app.cut("男默女泪", words);
+  //result << words;
+  //ASSERT_EQ("[\"男默女泪\"]", result);
+}