diff --git a/src/sql/engine/expr/ob_expr_cast.cpp b/src/sql/engine/expr/ob_expr_cast.cpp
index 2a301c4648..ff0bbde6c1 100644
--- a/src/sql/engine/expr/ob_expr_cast.cpp
+++ b/src/sql/engine/expr/ob_expr_cast.cpp
@@ -447,7 +447,11 @@ int ObExprCast::calc_result_type2(ObExprResType &type,
       // eg: select cast(18446744073709551615 as signed) -> -1
       //     because exprlicit case need CM_NO_RANGE_CHECK
       type_ctx.set_cast_mode(explicit_cast_cm & ~CM_EXPLICIT_CAST);
-      type1.set_calc_accuracy(type.get_accuracy());
+      if (lib::is_mysql_mode() && !ob_is_numeric_type(type.get_type()) && type1.is_double()) {
+        // for double type cast non-numeric type, no need set calc accuracy to dst type.
+      } else {
+        type1.set_calc_accuracy(type.get_accuracy());
+      }
 
       // in engine 3.0, let implicit cast do the real cast
       bool need_extra_cast_for_src_type = false;
diff --git a/src/sql/resolver/expr/ob_raw_expr_deduce_type.cpp b/src/sql/resolver/expr/ob_raw_expr_deduce_type.cpp
index 638027cdb6..ac2e1dad99 100644
--- a/src/sql/resolver/expr/ob_raw_expr_deduce_type.cpp
+++ b/src/sql/resolver/expr/ob_raw_expr_deduce_type.cpp
@@ -381,6 +381,9 @@ int ObRawExprDeduceType::calc_result_type(ObNonTerminalRawExpr &expr,
     // demands that we set the calculation type here.
     for (int64_t i = 0; i < types.count(); ++i) {
       types.at(i).set_calc_meta(types.at(i));
+      if (lib::is_mysql_mode() && types.at(i).is_double()) {
+        types.at(i).set_calc_accuracy(types.at(i).get_accuracy());
+      }
     }
     if (OB_FAIL(ret)) {
     } else if (ObExprOperator::NOT_ROW_DIMENSION != row_dimension) {
diff --git a/src/sql/resolver/expr/ob_raw_expr_util.cpp b/src/sql/resolver/expr/ob_raw_expr_util.cpp
index 5dc4974403..6021bb37d4 100644
--- a/src/sql/resolver/expr/ob_raw_expr_util.cpp
+++ b/src/sql/resolver/expr/ob_raw_expr_util.cpp
@@ -3441,11 +3441,13 @@ int ObRawExprUtils::try_add_cast_expr_above(ObRawExprFactory *expr_factory,
   int ret = OB_SUCCESS;
   new_expr = &expr;
   bool need_cast = false;
+  bool is_scale_adjust_cast = false;
   const ObExprResType &src_type = expr.get_result_type();
   CK(OB_NOT_NULL(session) && OB_NOT_NULL(expr_factory));
-  OZ(ObRawExprUtils::check_need_cast_expr(src_type, dst_type, need_cast));
+  OZ(ObRawExprUtils::check_need_cast_expr(src_type, dst_type, need_cast, is_scale_adjust_cast));
   if (OB_SUCC(ret) && need_cast) {
-    if (T_FUN_SYS_CAST == expr.get_expr_type() && expr.has_flag(IS_OP_OPERAND_IMPLICIT_CAST)) {
+    if (T_FUN_SYS_CAST == expr.get_expr_type() && expr.has_flag(IS_OP_OPERAND_IMPLICIT_CAST) &&
+          !is_scale_adjust_cast) {
       ret = OB_ERR_UNEXPECTED;
 #ifdef DEBUG
       LOG_ERROR("try to add implicit cast again, check if type deduction is correct",
@@ -6594,10 +6596,12 @@ bool ObRawExprUtils::is_sharable_expr(const ObRawExpr &expr)
 
 int ObRawExprUtils::check_need_cast_expr(const ObExprResType &src_type,
                                          const ObExprResType &dst_type,
-                                         bool &need_cast)
+                                         bool &need_cast,
+                                         bool &is_scale_adjust_cast)
 {
   int ret = OB_SUCCESS;
   need_cast = false;
+  is_scale_adjust_cast = false;
   ObObjType in_type  = src_type.get_type();
   ObObjType out_type = dst_type.get_type();
   ObCollationType in_cs_type  = src_type.get_collation_type();
@@ -6617,9 +6621,15 @@ int ObRawExprUtils::check_need_cast_expr(const ObExprResType &src_type,
           src_type.get_scale() != dst_type.get_scale() &&
           src_type.get_precision() != PRECISION_UNKNOWN_YET) {
       // for the conversion between doubles with increased scale in mysql mode,
-      // it is necessary to explicitly add the cast expression
+      // there are tow cases need to explicitly add the cast expression:
+      // case 1: the scale of dst_type is unknow(-1), the scale represents the largest float/double
+      //         scale in mysql.
+      // case 2: dst_scale is greater than src_scale, need to be aligned
       need_cast = (SCALE_UNKNOWN_YET == dst_type.get_scale()) ||
                      (src_type.get_scale() < dst_type.get_scale());
+      if (need_cast) {
+        is_scale_adjust_cast = true;
+      }
     }
   } else if (ob_is_enumset_tc(out_type)) {
     //no need add cast, will add column_conv later
diff --git a/src/sql/resolver/expr/ob_raw_expr_util.h b/src/sql/resolver/expr/ob_raw_expr_util.h
index 5937486a30..6986faa4ed 100644
--- a/src/sql/resolver/expr/ob_raw_expr_util.h
+++ b/src/sql/resolver/expr/ob_raw_expr_util.h
@@ -842,7 +842,8 @@ public:
 
   static int check_need_cast_expr(const ObExprResType &src_res_type,
                                   const ObExprResType &dst_res_type,
-                                  bool &need_cast);
+                                  bool &need_cast,
+                                  bool &is_scale_adjust_cast);
   static int build_add_expr(ObRawExprFactory &expr_factory,
                             ObRawExpr *param_expr1,
                             ObRawExpr *param_expr2,