diff --git a/include/cppjieba/DictTrie.hpp b/include/cppjieba/DictTrie.hpp
index f5c71902..3478db40 100644
--- a/include/cppjieba/DictTrie.hpp
+++ b/include/cppjieba/DictTrie.hpp
@@ -85,7 +85,7 @@ class DictTrie {
   {
     const DictUnit *tmp = NULL;
     RuneStrArray runes;
-    if (!DecodeRunesInString(word, runes))
+    if (!DecodeUTF8RunesInString(word, runes))
     {
       XLOG(ERROR) << "Decode failed.";
     }
@@ -197,7 +197,7 @@ class DictTrie {
         const string& word, 
         double weight, 
         const string& tag) {
-    if (!DecodeRunesInString(word, node_info.word)) {
+    if (!DecodeUTF8RunesInString(word, node_info.word)) {
       XLOG(ERROR) << "Decode " << word << " failed.";
       return false;
     }
diff --git a/include/cppjieba/HMMModel.hpp b/include/cppjieba/HMMModel.hpp
index 27e6b662..3921faaf 100644
--- a/include/cppjieba/HMMModel.hpp
+++ b/include/cppjieba/HMMModel.hpp
@@ -105,7 +105,7 @@ struct HMMModel {
         XLOG(ERROR) << "emitProb illegal.";
         return false;
       }
-      if (!DecodeRunesInString(tmp2[0], unicode) || unicode.size() != 1) {
+      if (!DecodeUTF8RunesInString(tmp2[0], unicode) || unicode.size() != 1) {
         XLOG(ERROR) << "TransCode failed.";
         return false;
       }
diff --git a/include/cppjieba/PosTagger.hpp b/include/cppjieba/PosTagger.hpp
index 78853d53..a6810b2d 100644
--- a/include/cppjieba/PosTagger.hpp
+++ b/include/cppjieba/PosTagger.hpp
@@ -34,7 +34,7 @@ class PosTagger {
     RuneStrArray runes;
     const DictTrie * dict = segment.GetDictTrie();
     assert(dict != NULL);
-      if (!DecodeRunesInString(str, runes)) {
+      if (!DecodeUTF8RunesInString(str, runes)) {
         XLOG(ERROR) << "Decode failed.";
         return POS_X;
       }
diff --git a/include/cppjieba/PreFilter.hpp b/include/cppjieba/PreFilter.hpp
index ecb81c0b..e73b9ab5 100644
--- a/include/cppjieba/PreFilter.hpp
+++ b/include/cppjieba/PreFilter.hpp
@@ -17,7 +17,7 @@ class PreFilter {
   PreFilter(const unordered_set<Rune>& symbols, 
         const string& sentence)
     : symbols_(symbols) {
-    if (!DecodeRunesInString(sentence, sentence_)) {
+    if (!DecodeUTF8RunesInString(sentence, sentence_)) {
       XLOG(ERROR) << "decode failed. "; 
     }
     cursor_ = sentence_.begin();
diff --git a/include/cppjieba/SegmentBase.hpp b/include/cppjieba/SegmentBase.hpp
index 79c80094..2885b83e 100644
--- a/include/cppjieba/SegmentBase.hpp
+++ b/include/cppjieba/SegmentBase.hpp
@@ -25,7 +25,7 @@ class SegmentBase {
   bool ResetSeparators(const string& s) {
     symbols_.clear();
     RuneStrArray runes;
-    if (!DecodeRunesInString(s, runes)) {
+    if (!DecodeUTF8RunesInString(s, runes)) {
       XLOG(ERROR) << "decode " << s << " failed";
       return false;
     }
diff --git a/include/cppjieba/Unicode.hpp b/include/cppjieba/Unicode.hpp
index 7f064569..9adec2ca 100644
--- a/include/cppjieba/Unicode.hpp
+++ b/include/cppjieba/Unicode.hpp
@@ -84,7 +84,7 @@ struct RuneStrLite {
   }
 }; // struct RuneStrLite
 
-inline RuneStrLite DecodeRuneInString(const char* str, size_t len) {
+inline RuneStrLite DecodeUTF8ToRune(const char* str, size_t len) {
   RuneStrLite rp(0, 0);
   if (str == NULL || len == 0) {
     return rp;
@@ -139,11 +139,11 @@ inline RuneStrLite DecodeRuneInString(const char* str, size_t len) {
   return rp;
 }
 
-inline bool DecodeRunesInString(const char* s, size_t len, RuneStrArray& runes) {
+inline bool DecodeUTF8RunesInString(const char* s, size_t len, RuneStrArray& runes) {
   runes.clear();
   runes.reserve(len / 2);
   for (uint32_t i = 0, j = 0; i < len;) {
-    RuneStrLite rp = DecodeRuneInString(s + i, len - i);
+    RuneStrLite rp = DecodeUTF8ToRune(s + i, len - i);
     if (rp.len == 0) {
       runes.clear();
       return false;
@@ -156,14 +156,14 @@ inline bool DecodeRunesInString(const char* s, size_t len, RuneStrArray& runes)
   return true;
 }
 
-inline bool DecodeRunesInString(const string& s, RuneStrArray& runes) {
-  return DecodeRunesInString(s.c_str(), s.size(), runes);
+inline bool DecodeUTF8RunesInString(const string& s, RuneStrArray& runes) {
+  return DecodeUTF8RunesInString(s.c_str(), s.size(), runes);
 }
 
-inline bool DecodeRunesInString(const char* s, size_t len, Unicode& unicode) {
+inline bool DecodeUTF8RunesInString(const char* s, size_t len, Unicode& unicode) {
   unicode.clear();
   RuneStrArray runes;
-  if (!DecodeRunesInString(s, len, runes)) {
+  if (!DecodeUTF8RunesInString(s, len, runes)) {
     return false;
   }
   unicode.reserve(runes.size());
@@ -174,17 +174,17 @@ inline bool DecodeRunesInString(const char* s, size_t len, Unicode& unicode) {
 }
 
 inline bool IsSingleWord(const string& str) {
-  RuneStrLite rp = DecodeRuneInString(str.c_str(), str.size());
+  RuneStrLite rp = DecodeUTF8ToRune(str.c_str(), str.size());
   return rp.len == str.size();
 }
 
-inline bool DecodeRunesInString(const string& s, Unicode& unicode) {
-  return DecodeRunesInString(s.c_str(), s.size(), unicode);
+inline bool DecodeUTF8RunesInString(const string& s, Unicode& unicode) {
+  return DecodeUTF8RunesInString(s.c_str(), s.size(), unicode);
 }
 
-inline Unicode DecodeRunesInString(const string& s) {
+inline Unicode DecodeUTF8RunesInString(const string& s) {
   Unicode result;
-  DecodeRunesInString(s, result);
+  DecodeUTF8RunesInString(s, result);
   return result;
 }
 
diff --git a/test/unittest/trie_test.cpp b/test/unittest/trie_test.cpp
index 1f035406..2e519930 100644
--- a/test/unittest/trie_test.cpp
+++ b/test/unittest/trie_test.cpp
@@ -15,7 +15,7 @@ TEST(TrieTest, Empty) {
 TEST(TrieTest, Construct) {
   vector<Unicode> keys;
   vector<const DictUnit*> values;
-  keys.push_back(DecodeRunesInString("你"));
+  keys.push_back(DecodeUTF8RunesInString("你"));
   values.push_back((const DictUnit*)(NULL));
   Trie trie(keys, values);
 }
@@ -32,7 +32,7 @@ TEST(DictTrieTest, Test1) {
   ASSERT_LT(trie.GetMinWeight() + 15.6479, 0.001);
   string word("来到");
   cppjieba::RuneStrArray uni;
-  ASSERT_TRUE(DecodeRunesInString(word, uni));
+  ASSERT_TRUE(DecodeUTF8RunesInString(word, uni));
   //DictUnit nodeInfo;
   //nodeInfo.word = uni;
   //nodeInfo.tag = "v";
@@ -52,13 +52,13 @@ TEST(DictTrieTest, Test1) {
   LocalVector<pair<size_t, const DictUnit*> > res;
   const char * words[] = {"清", "清华", "清华大学"};
   for (size_t i = 0; i < sizeof(words)/sizeof(words[0]); i++) {
-    ASSERT_TRUE(DecodeRunesInString(words[i], uni));
+    ASSERT_TRUE(DecodeUTF8RunesInString(words[i], uni));
     res.push_back(make_pair(uni.size() - 1, trie.Find(uni.begin(), uni.end())));
     //resMap[uni.size() - 1] = trie.Find(uni.begin(), uni.end());
   }
   vector<pair<size_t, const DictUnit*> > vec;
   vector<struct Dag> dags;
-  ASSERT_TRUE(DecodeRunesInString(word, uni));
+  ASSERT_TRUE(DecodeUTF8RunesInString(word, uni));
   trie.Find(uni.begin(), uni.end(), dags);
   ASSERT_EQ(dags.size(), uni.size());
   ASSERT_NE(dags.size(), 0u);
@@ -72,20 +72,20 @@ TEST(DictTrieTest, UserDict) {
   DictTrie trie(DICT_FILE, "../test/testdata/userdict.utf8");
   string word = "云计算";
   cppjieba::RuneStrArray unicode;
-  ASSERT_TRUE(DecodeRunesInString(word, unicode));
+  ASSERT_TRUE(DecodeUTF8RunesInString(word, unicode));
   const DictUnit * unit = trie.Find(unicode.begin(), unicode.end());
   ASSERT_TRUE(unit != NULL);
   ASSERT_NEAR(unit->weight, -14.100, 0.001);
 
   word = "蓝翔";
-  ASSERT_TRUE(DecodeRunesInString(word, unicode));
+  ASSERT_TRUE(DecodeUTF8RunesInString(word, unicode));
   unit = trie.Find(unicode.begin(), unicode.end());
   ASSERT_TRUE(unit != NULL);
   ASSERT_EQ(unit->tag, "nz");
   ASSERT_NEAR(unit->weight, -14.100, 0.001);
 
   word = "区块链";
-  ASSERT_TRUE(DecodeRunesInString(word, unicode));
+  ASSERT_TRUE(DecodeUTF8RunesInString(word, unicode));
   unit = trie.Find(unicode.begin(), unicode.end());
   ASSERT_TRUE(unit != NULL);
   ASSERT_EQ(unit->tag, "nz");
@@ -96,7 +96,7 @@ TEST(DictTrieTest, UserDictWithMaxWeight) {
   DictTrie trie(DICT_FILE, "../test/testdata/userdict.utf8", DictTrie::WordWeightMax);
   string word = "云计算";
   cppjieba::RuneStrArray unicode;
-  ASSERT_TRUE(DecodeRunesInString(word, unicode));
+  ASSERT_TRUE(DecodeUTF8RunesInString(word, unicode));
   const DictUnit * unit = trie.Find(unicode.begin(), unicode.end());
   ASSERT_TRUE(unit);
   ASSERT_NEAR(unit->weight, -2.975, 0.001);
@@ -108,7 +108,7 @@ TEST(DictTrieTest, Dag) {
   {
     string word = "清华大学";
     cppjieba::RuneStrArray unicode;
-    ASSERT_TRUE(DecodeRunesInString(word, unicode));
+    ASSERT_TRUE(DecodeUTF8RunesInString(word, unicode));
     vector<struct Dag> res;
     trie.Find(unicode.begin(), unicode.end(), res);
 
@@ -122,7 +122,7 @@ TEST(DictTrieTest, Dag) {
   {
     string word = "北京邮电大学";
     cppjieba::RuneStrArray unicode;
-    ASSERT_TRUE(DecodeRunesInString(word, unicode));
+    ASSERT_TRUE(DecodeUTF8RunesInString(word, unicode));
     vector<struct Dag> res;
     trie.Find(unicode.begin(), unicode.end(), res);
 
@@ -136,7 +136,7 @@ TEST(DictTrieTest, Dag) {
   {
     string word = "长江大桥";
     cppjieba::RuneStrArray unicode;
-    ASSERT_TRUE(DecodeRunesInString(word, unicode));
+    ASSERT_TRUE(DecodeUTF8RunesInString(word, unicode));
     vector<struct Dag> res;
     trie.Find(unicode.begin(), unicode.end(), res);
 
@@ -150,7 +150,7 @@ TEST(DictTrieTest, Dag) {
   {
     string word = "长江大桥";
     cppjieba::RuneStrArray unicode;
-    ASSERT_TRUE(DecodeRunesInString(word, unicode));
+    ASSERT_TRUE(DecodeUTF8RunesInString(word, unicode));
     vector<struct Dag> res;
     trie.Find(unicode.begin(), unicode.end(), res, 3);
 
@@ -164,7 +164,7 @@ TEST(DictTrieTest, Dag) {
   {
     string word = "长江大桥";
     cppjieba::RuneStrArray unicode;
-    ASSERT_TRUE(DecodeRunesInString(word, unicode));
+    ASSERT_TRUE(DecodeUTF8RunesInString(word, unicode));
     vector<struct Dag> res;
     trie.Find(unicode.begin(), unicode.end(), res, 4);
 
diff --git a/test/unittest/unicode_test.cpp b/test/unittest/unicode_test.cpp
index a22096e9..89113b9d 100644
--- a/test/unittest/unicode_test.cpp
+++ b/test/unittest/unicode_test.cpp
@@ -8,7 +8,7 @@ using namespace std;
 TEST(UnicodeTest, Test1) {
   string s = "你好世界";
   RuneStrArray runes;
-  ASSERT_TRUE(DecodeRunesInString(s, runes));
+  ASSERT_TRUE(DecodeUTF8RunesInString(s, runes));
   string actual;
   string expected = "[\"{\"rune\": \"20320\", \"offset\": 0, \"len\": 3}\", \"{\"rune\": \"22909\", \"offset\": 3, \"len\": 3}\", \"{\"rune\": \"19990\", \"offset\": 6, \"len\": 3}\", \"{\"rune\": \"30028\", \"offset\": 9, \"len\": 3}\"]";
   actual << runes;
@@ -18,7 +18,7 @@ TEST(UnicodeTest, Test1) {
 TEST(UnicodeTest, Illegal) {
   string s = "123\x80";
   RuneStrArray runes;
-  ASSERT_FALSE(DecodeRunesInString(s, runes));
+  ASSERT_FALSE(DecodeUTF8RunesInString(s, runes));
   string actual;
   string expected = "[]";
   actual << runes;
@@ -38,6 +38,6 @@ TEST(UnicodeTest, Rand) {
       s[rand() % len] = rand();
     }
     RuneStrArray runes;
-    DecodeRunesInString(s, runes);
+    DecodeUTF8RunesInString(s, runes);
   }
 }