diff --git a/paddle/fluid/operators/string/faster_tokenizer_op.cc b/paddle/fluid/operators/string/faster_tokenizer_op.cc
index 49457af8f00c80debabf4ed76e456dacc580be00..42047021b408a8bd2582d68faaf814ff145dc1a0 100644
--- a/paddle/fluid/operators/string/faster_tokenizer_op.cc
+++ b/paddle/fluid/operators/string/faster_tokenizer_op.cc
@@ -100,9 +100,14 @@ void BasicTokenizer::Tokenize(const string& text, vector<wstring>* res) const {
     // String is converted into wstring failedly.
     return;
   }
-
-  std::wstring dest_text;
-  for (auto ch : unicode_text) {
+  std::wstring cache_text = L"";
+  auto PushCacheText = [&]() {
+    if (cache_text != L"") {
+      res->emplace_back(cache_text);
+      cache_text = L"";
+    }
+  };
+  for (auto& ch : unicode_text) {
     if (ch == 0 || ch == 0xfffd || IsControl(ch)) {
       continue;
     }
@@ -110,25 +115,24 @@ void BasicTokenizer::Tokenize(const string& text, vector<wstring>* res) const {
       ch = do_lower_case(ch);
     }
     if (IsChineseChar(ch) || IsPunctuation(ch)) {
-      dest_text += ' ';
-      dest_text += ch;
-      dest_text += ' ';
+      PushCacheText();
+      res->emplace_back(std::wstring{ch});
     } else if (IsWhiteSpace(ch)) {
-      dest_text += ' ';
+      PushCacheText();
     } else {
-      dest_text += ch;
+      cache_text += ch;
     }
   }
-  boost::split(*res, dest_text, boost::is_any_of(kStripChars));
+  PushCacheText();
 }
 
 WordPieceTokenizer::WordPieceTokenizer(
-    framework::Vocab* vocab, const wstring& unk_token /* = L"[UNK]"*/,
+    const framework::Vocab* vocab, const wstring& unk_token /* = L"[UNK]"*/,
     const size_t max_input_chars_per_word /* = 100 */)
     : vocab_(vocab),
       unk_token_(unk_token),
       max_input_chars_per_word_(max_input_chars_per_word) {
-  unk_token_id_ = (*vocab_)[unk_token_];
+  unk_token_id_ = vocab_->at(unk_token_);
 }
 
 void WordPieceTokenizer::Tokenize(const wstring& text,
@@ -178,7 +182,7 @@ void WordPieceTokenizer::Tokenize(const wstring& text,
   }
 }
 
-BertTokenizer::BertTokenizer(framework::Vocab* vocab,
+BertTokenizer::BertTokenizer(const framework::Vocab* vocab,
                              bool do_lower_case /* = false */,
                              const wstring& unk_token /* = L"[UNK]" */,
                              const wstring& pad_token /* = L"[PAD]" */,
@@ -196,11 +200,11 @@ BertTokenizer::BertTokenizer(framework::Vocab* vocab,
       vocab_(vocab),
       basic_tokenizer_(do_lower_case_),
       word_piece_tokenizer_(vocab_, unk_token) {
-  unk_token_id_ = (*vocab_)[unk_token_];
-  pad_token_id_ = (*vocab_)[pad_token_];
-  cls_token_id_ = (*vocab_)[cls_token_];
-  mask_token_id_ = (*vocab_)[mask_token_];
-  sep_token_id_ = (*vocab_)[sep_token_];
+  unk_token_id_ = vocab_->at(unk_token_);
+  pad_token_id_ = vocab_->at(pad_token_);
+  cls_token_id_ = vocab_->at(cls_token_);
+  mask_token_id_ = vocab_->at(mask_token_);
+  sep_token_id_ = vocab_->at(sep_token_);
 
   all_special_tokens_ = vector<wstring>(
       {unk_token_, pad_token_, cls_token_, mask_token_, sep_token_});
diff --git a/paddle/fluid/operators/string/faster_tokenizer_op.h b/paddle/fluid/operators/string/faster_tokenizer_op.h
old mode 100755
new mode 100644
index d9b7fa26a6704b82bb5e9911109f0064260db3b7..5218b7c2eaa51da062dff1ac80d08b0b2e50d906
--- a/paddle/fluid/operators/string/faster_tokenizer_op.h
+++ b/paddle/fluid/operators/string/faster_tokenizer_op.h
@@ -56,13 +56,13 @@ class BasicTokenizer {
 
 class WordPieceTokenizer {
  public:
-  explicit WordPieceTokenizer(framework::Vocab* vocab,
+  explicit WordPieceTokenizer(const framework::Vocab* vocab,
                               const wstring& unk_token = L"[UNK]",
                               const size_t max_input_chars_per_word = 100);
   void Tokenize(const wstring& text, vector<int64_t>* output) const;
 
  private:
-  framework::Vocab* vocab_;
+  const framework::Vocab* vocab_;
   wstring unk_token_{L"[UNK]"};
   int64_t unk_token_id_;
   size_t max_input_chars_per_word_;
@@ -70,7 +70,8 @@ class WordPieceTokenizer {
 
 class BertTokenizer {
  public:
-  explicit BertTokenizer(framework::Vocab* vocab, bool do_lower_case = false,
+  explicit BertTokenizer(const framework::Vocab* vocab,
+                         bool do_lower_case = false,
                          const wstring& unk_token = L"[UNK]",
                          const wstring& pad_token = L"[PAD]",
                          const wstring& cls_token = L"[CLS]",
@@ -106,7 +107,7 @@ class BertTokenizer {
   bool do_lower_case_;
   wstring unk_token_, pad_token_, cls_token_, mask_token_, sep_token_;
   string padding_site_;
-  framework::Vocab* vocab_;
+  const framework::Vocab* vocab_;
   BasicTokenizer basic_tokenizer_;
   WordPieceTokenizer word_piece_tokenizer_;
   int64_t unk_token_id_, cls_token_id_, mask_token_id_, pad_token_id_,
@@ -140,21 +141,20 @@ class FasterTokenizerKernel : public framework::OpKernel<T> {
       return;
     }
 
-    BertTokenizer* tokenizer_ptr =
-        new BertTokenizer(const_cast<framework::Vocab*>(vocab), do_lower_case);
+    BertTokenizer tokenizer(vocab, do_lower_case);
     size_t batch_max_seq_len = 0;
     size_t batch_size = text->size();
 
     vector<unordered_map<string, vector<int64_t>>> batch_encode_inputs(
         batch_size);
     if (text_pair) {
-      tokenizer_ptr->BatchEncode(&batch_encode_inputs, *text, *text_pair,
-                                 is_split_into_words, max_seq_len,
-                                 pad_to_max_seq_len);
+      tokenizer.BatchEncode(&batch_encode_inputs, *text, *text_pair,
+                            is_split_into_words, max_seq_len,
+                            pad_to_max_seq_len);
     } else {
-      tokenizer_ptr->BatchEncode(&batch_encode_inputs, *text, vector<string>(),
-                                 is_split_into_words, max_seq_len,
-                                 pad_to_max_seq_len);
+      tokenizer.BatchEncode(&batch_encode_inputs, *text, vector<string>(),
+                            is_split_into_words, max_seq_len,
+                            pad_to_max_seq_len);
     }
 
     for (size_t i = 0; i < batch_size; ++i) {
@@ -173,7 +173,7 @@ class FasterTokenizerKernel : public framework::OpKernel<T> {
                               static_cast<int64_t>(batch_max_seq_len)}));
     auto* seg_ids_data = seg_ids->mutable_data<T>(ctx.GetPlace());
 
-    auto pad_token_id = tokenizer_ptr->GetPadTokenID();
+    auto pad_token_id = tokenizer.GetPadTokenID();
     for (size_t i = 0; i < batch_size; i++) {
       auto& encoder_input_ids = batch_encode_inputs[i]["input_ids"];
       auto& encoder_seg_ids = batch_encode_inputs[i]["token_type_ids"];
@@ -188,7 +188,6 @@ class FasterTokenizerKernel : public framework::OpKernel<T> {
       std::memset(seg_ids_data + i * batch_max_seq_len + seq_len, pad_token_id,
                   (batch_max_seq_len - seq_len) * sizeof(T));
     }
-    delete tokenizer_ptr;
   }
 };