diff --git a/src/pl/parser/parse_stmt_node.h b/src/pl/parser/parse_stmt_node.h
index 4b06fbac64..11dec8275b 100644
--- a/src/pl/parser/parse_stmt_node.h
+++ b/src/pl/parser/parse_stmt_node.h
@@ -66,7 +66,7 @@ typedef struct _ObParseCtx
   int comp_mode_;
   bool is_not_utf8_connection_;
   const struct ObCharsetInfo *charset_info_;
-  int64_t last_well_formed_len_;  //解析quoted string时的一个临时变量，处理连接gbk字符集时遇到的转义字符问题
+  int64_t last_escape_check_pos_;  //解析quoted string时的一个临时变量，处理连接gbk字符集时遇到的转义字符问题
   int connection_collation_;
   bool mysql_compatible_comment_; //whether the parser is parsing "/*! xxxx */"
   struct
diff --git a/src/sql/parser/ob_fast_parser.cpp b/src/sql/parser/ob_fast_parser.cpp
index 2eb66cce4c..4b453073de 100644
--- a/src/sql/parser/ob_fast_parser.cpp
+++ b/src/sql/parser/ob_fast_parser.cpp
@@ -82,7 +82,7 @@ ObFastParserBase::ObFastParserBase(
   is_batched_multi_stmt_split_on_(enable_batched_multi_stmt),
   is_mysql_compatible_comment_(false),
   cur_token_begin_pos_(0), copy_begin_pos_(0), copy_end_pos_(0),
-  tmp_buf_(nullptr), tmp_buf_len_(0), last_well_formed_len_(0),
+  tmp_buf_(nullptr), tmp_buf_len_(0), last_escape_check_pos_(0),
   param_node_list_(nullptr), tail_param_node_(nullptr),
   cur_token_type_(INVALID_TOKEN), allocator_(allocator),
   parse_next_token_func_(nullptr), process_idf_func_(nullptr)
@@ -1382,22 +1382,21 @@ inline void ObFastParserBase::check_real_escape(bool &is_real_escape)
 {
   if (OB_NOT_NULL(charset_info_) && charset_info_->escape_with_backslash_is_dangerous) {
     char *cur_pos = tmp_buf_ + tmp_buf_len_;
-    char *last_check_pos = tmp_buf_ + last_well_formed_len_;
+    char *last_check_pos = tmp_buf_ + last_escape_check_pos_;
     int error = 0;
     int expected_well_formed_len = cur_pos - last_check_pos;
-    int real_well_formed_len = charset_info_->cset->well_formed_len(
-                charset_info_, last_check_pos, cur_pos, UINT64_MAX, &error);
-    if (error != 0) {
+
+    while (last_check_pos < cur_pos) {
+      size_t real_well_formed_len = charset_info_->cset->well_formed_len(
+                  charset_info_, last_check_pos, cur_pos, UINT64_MAX, &error);
+      last_check_pos += (real_well_formed_len + ((error != 0) ? 1 : 0));
+    }
+
+    if (error != 0) { //the final well-formed result
       *cur_pos = '\\';
-      if (real_well_formed_len == expected_well_formed_len - 1
-          && charset_info_->cset->ismbchar(charset_info_, cur_pos - 1, cur_pos + 1)) {
+      if (charset_info_->cset->ismbchar(charset_info_, cur_pos - 1, cur_pos + 1)) {
         is_real_escape = false;
-        last_well_formed_len_ = tmp_buf_len_ + 1;
-      } else {
-        last_well_formed_len_ = tmp_buf_len_;
       }
-    } else {
-      last_well_formed_len_ = tmp_buf_len_;
     }
   }
 }
@@ -1826,7 +1825,7 @@ int ObFastParserMysql::process_string(const char quote)
   ParseNode **child_node = NULL;
   char ch = INVALID_CHAR;
   tmp_buf_len_ = 0;
-  last_well_formed_len_ = 0;
+  last_escape_check_pos_ = 0;
   if (nullptr == tmp_buf_ &&
       OB_ISNULL(tmp_buf_ = static_cast<char *>(allocator_.alloc(raw_sql_.raw_sql_len_ + 1)))) {
     ret = OB_ALLOCATE_MEMORY_FAILED;
@@ -1855,6 +1854,7 @@ int ObFastParserMysql::process_string(const char quote)
         } else {
           process_escape_string(tmp_buf_, tmp_buf_len_);
         }
+        last_escape_check_pos_ = tmp_buf_len_;
       } else if (quote == ch) {
         if (quote == raw_sql_.peek()) { // double quote
           ch = raw_sql_.scan();
diff --git a/src/sql/parser/ob_fast_parser.h b/src/sql/parser/ob_fast_parser.h
index 4b6db13f1b..0922ad8e02 100644
--- a/src/sql/parser/ob_fast_parser.h
+++ b/src/sql/parser/ob_fast_parser.h
@@ -495,7 +495,7 @@ protected:
 	int64_t copy_end_pos_;
 	char *tmp_buf_;
 	int64_t tmp_buf_len_;
-	int64_t last_well_formed_len_;
+	int64_t last_escape_check_pos_;
 	ParamList *param_node_list_;
 	ParamList *tail_param_node_;
 	TokenType cur_token_type_;
diff --git a/src/sql/parser/parse_malloc.cpp b/src/sql/parser/parse_malloc.cpp
index 7a9585c008..4b12035b96 100644
--- a/src/sql/parser/parse_malloc.cpp
+++ b/src/sql/parser/parse_malloc.cpp
@@ -267,27 +267,24 @@ char *parse_strdup_with_replace_multi_byte_char(const char *str, int *connection
 }
 
 bool check_real_escape(const ObCharsetInfo *cs, char *str, int64_t str_len,
-                       int64_t *last_well_formed_len)
+                       int64_t last_escape_check_pos)
 {
   bool is_real_escape = true;
-  if (NULL != cs && NULL != last_well_formed_len && cs->escape_with_backslash_is_dangerous) {
+  if (NULL != cs && cs->escape_with_backslash_is_dangerous) {
     char *cur_pos = str + str_len;
-    char *last_check_pos = str + *last_well_formed_len;
+    char *last_check_pos = str + last_escape_check_pos;
     int error = 0;
     size_t expected_well_formed_len = cur_pos - last_check_pos;
-    size_t real_well_formed_len = cs->cset->well_formed_len(
-                cs, last_check_pos, cur_pos, UINT64_MAX, &error);
-    if (error != 0) {
+    while (last_check_pos < cur_pos) {
+      size_t real_well_formed_len = cs->cset->well_formed_len(
+                  cs, last_check_pos, cur_pos, UINT64_MAX, &error);
+      last_check_pos += (real_well_formed_len + ((error != 0) ? 1 : 0));
+    }
+    if (error != 0) { //the final well-formed result
       *cur_pos = '\\';
-      if (real_well_formed_len == expected_well_formed_len - 1
-          && cs->cset->ismbchar(cs, cur_pos - 1, cur_pos + 1)) {
+      if (cs->cset->ismbchar(cs, cur_pos - 1, cur_pos + 1)) {
         is_real_escape = false;
-        *last_well_formed_len = str_len + 1;
-      } else {
-        *last_well_formed_len = str_len;
       }
-    } else {
-      *last_well_formed_len = str_len;
     }
   }
   return is_real_escape;
diff --git a/src/sql/parser/parse_malloc.h b/src/sql/parser/parse_malloc.h
index 193347be87..feeee14c58 100644
--- a/src/sql/parser/parse_malloc.h
+++ b/src/sql/parser/parse_malloc.h
@@ -35,7 +35,7 @@ extern char *cp_str_value(const char *src, const size_t nbyte, void *malloc_pool
 extern char *parse_strdup_with_replace_multi_byte_char(const char *str, int *connection_collation_,
                                                        void *malloc_pool, int64_t *out_len);
 extern bool check_real_escape(const struct ObCharsetInfo *cs, char *str, int64_t str_len,
-                              int64_t *last_well_formed_len);
+                              int64_t last_escape_check_pos);
 extern void *parser_alloc(void *malloc_pool, const int64_t alloc_size);
 
 extern void *malloc_parentheses_info(const size_t nbyte, void *malloc_pool);
diff --git a/src/sql/parser/parse_node.h b/src/sql/parser/parse_node.h
index 34c8af527a..e66602c4c6 100644
--- a/src/sql/parser/parse_node.h
+++ b/src/sql/parser/parse_node.h
@@ -321,7 +321,7 @@ typedef struct
   PLParseInfo pl_parse_info_;
   /*for  q-quote*/
   ObMinusStatusCtx minus_ctx_; // for fast parser to parse negative value
-  int64_t last_well_formed_len_;  //解析quoted string%parse-param时的一个临时变量，处理连接gbk字符集时遇到的转义字符问题
+  int64_t last_escape_check_pos_;  //解析quoted string%parse-param时的一个临时变量，处理连接gbk字符集时遇到的转义字符问题
   int connection_collation_;//connection collation
   bool mysql_compatible_comment_; //whether the parser is parsing "/*! xxxx */"
   bool enable_compatible_comment_;
diff --git a/src/sql/parser/sql_parser_base.h b/src/sql/parser/sql_parser_base.h
index 7b09de3520..4c105b2e36 100644
--- a/src/sql/parser/sql_parser_base.h
+++ b/src/sql/parser/sql_parser_base.h
@@ -64,7 +64,7 @@ extern int64_t ob_strntoll(const char *ptr, size_t len, int base, char **end, in
 extern int64_t ob_strntoull(const char *ptr, size_t len, int base, char **end, int *err);
 extern int store_prentthese_info(int left, int right, ParseResult *result);
 extern bool check_real_escape(const struct ObCharsetInfo *cs, char *str, int64_t str_len,
-                              int64_t *last_well_formed_len);
+                              int64_t last_escape_check_pos);
 
 int add_alias_name(ParseNode *node, ParseResult *result, int end);
 
@@ -692,7 +692,7 @@ do {
 
 #define CHECK_REAL_ESCAPE(is_real_escape)                                         \
   is_real_escape = check_real_escape(p->charset_info_, p->tmp_literal_,           \
-                                     yylval->node->str_len_, &(p->last_well_formed_len_))
+                                     yylval->node->str_len_, p->last_escape_check_pos_)
   /*
 do {                                                                              \
   if (NULL !=  p->charset_info_ && p->charset_info_->escape_with_backslash_is_dangerous) { \
diff --git a/src/sql/parser/sql_parser_mysql_mode.l b/src/sql/parser/sql_parser_mysql_mode.l
index 7d0ca2ff1f..cc27b6c93e 100644
--- a/src/sql/parser/sql_parser_mysql_mode.l
+++ b/src/sql/parser/sql_parser_mysql_mode.l
@@ -264,7 +264,7 @@ FALSE {
   check_value(yylval);
   malloc_new_node(yylval->node, p->malloc_pool_, T_VARCHAR, 0);
   yylval->node->str_len_ = 0;
-  p->last_well_formed_len_ = 0;
+  p->last_escape_check_pos_ = 0;
   yylval->node->str_value_ = NULL;
   if (IS_FAST_PARAMETERIZE && !IS_NEED_PARAMETERIZE) {
     COPY_WRITE();
@@ -327,6 +327,7 @@ FALSE {
   } else {
     HANDLE_ESCAPE(p);
   }
+  p->last_escape_check_pos_ = yylval->node->str_len_;
   if (IS_FAST_PARAMETERIZE && !IS_NEED_PARAMETERIZE) {
     COPY_WRITE();
   }
@@ -408,7 +409,7 @@ FALSE {
     }
     malloc_new_node(yylval->node, p->malloc_pool_, T_VARCHAR, 0);
     yylval->node->str_len_ = 0;
-    p->last_well_formed_len_ = 0;
+    p->last_escape_check_pos_ = 0;
     if (IS_FAST_PARAMETERIZE && !IS_NEED_PARAMETERIZE) {
       return OUTLINE_DEFAULT_TOKEN;
     }
@@ -476,6 +477,7 @@ FALSE {
   } else {
     HANDLE_ESCAPE(p);
   }
+  p->last_escape_check_pos_ = yylval->node->str_len_;
   if (IS_FAST_PARAMETERIZE && !IS_NEED_PARAMETERIZE) {
     return OUTLINE_DEFAULT_TOKEN;
   }
@@ -1059,7 +1061,7 @@ Timestamp{whitespace}?\"[^\"]*\" {
   check_value(yylval);
   malloc_new_node(yylval->node, p->malloc_pool_, T_VARCHAR, 0);
   yylval->node->str_len_ = 0;
-  p->last_well_formed_len_ = 0;
+  p->last_escape_check_pos_ = 0;
   yylval->node->str_value_ = NULL;
   if (IS_FAST_PARAMETERIZE && !IS_NEED_PARAMETERIZE && !p->is_ignore_token_) {
     COPY_WRITE();