diff --git a/deps/oblib/src/common/cell/ob_cell_writer.cpp b/deps/oblib/src/common/cell/ob_cell_writer.cpp
index 02bd6bb9b2..836a7f3ca9 100644
--- a/deps/oblib/src/common/cell/ob_cell_writer.cpp
+++ b/deps/oblib/src/common/cell/ob_cell_writer.cpp
@@ -12,6 +12,7 @@
 
 #include "common/cell/ob_cell_writer.h"
 #include "common/object/ob_object.h"
+#include "lib/timezone/ob_time_convert.h"
 namespace oceanbase
 {
 namespace common
@@ -505,7 +506,7 @@ int ObCellWriter::append(uint64_t column_id, const ObObj &obj, ObObj *clone_obj)
         WRITE_DATA(ObTimestampType, 0, int64_t, obj.get_timestamp());
         break;
       case ObTimeType: {
-        const int64_t ob_time_max_value = 3020399999999;  // 838:59:59
+        const int64_t ob_time_max_value = TIME_MAX_VAL;
         assert(obj.get_time() <= ob_time_max_value && obj.get_time() >= -ob_time_max_value);
         WRITE_DATA(ObTimeType, 0, int64_t, obj.get_time());
         break;
diff --git a/deps/oblib/src/lib/timezone/ob_time_convert.cpp b/deps/oblib/src/lib/timezone/ob_time_convert.cpp
index addda5350d..abe71d30b1 100644
--- a/deps/oblib/src/lib/timezone/ob_time_convert.cpp
+++ b/deps/oblib/src/lib/timezone/ob_time_convert.cpp
@@ -792,8 +792,7 @@ int ObTimeConverter::str_to_date(const ObString &str, int32_t &value,
   return ret;
 }
 
-int ObTimeConverter::str_to_time(const ObString &str, int64_t &value, int16_t *scale,
-                                 const ObScale &time_scale, const bool &need_truncate)
+int ObTimeConverter::str_to_time(const ObString &str, int64_t &value, int16_t *scale, const bool &need_truncate)
 {
   int ret = OB_SUCCESS;
   ObTime ob_time(DT_TYPE_TIME);
@@ -801,14 +800,14 @@ int ObTimeConverter::str_to_time(const ObString &str, int64_t &value, int16_t *s
     LOG_WARN("failed to convert string to time", K(ret), K(str));
     if (OB_ERR_TRUNCATED_WRONG_VALUE == ret) {
       value = ob_time_to_time(ob_time);
-      time_overflow_trunc(value, time_scale);
+      time_overflow_trunc(value);
       if (DT_MODE_NEG & ob_time.mode_) {
         value = -value;
       }
     }
   } else {
     value = ob_time_to_time(ob_time);
-    ret = time_overflow_trunc(value, time_scale);
+    ret = time_overflow_trunc(value);
     if (DT_MODE_NEG & ob_time.mode_) {
       value = -value;
     }
@@ -5386,8 +5385,7 @@ int ObTimeConverter::set_ob_time_year_may_conflict(ObTime &ob_time, int32_t &jul
 int ObTimeConverter::time_overflow_trunc(int64_t &value, const ObScale &time_scale)
 {
   int ret = OB_SUCCESS;
-  int64_t increment = (6 == time_scale) ? 999999 : 0;
-  if (value > (TIME_MAX_VAL + increment)) {
+  if (value > TIME_MAX_VAL) {
     // we need some ob error codes that map to ER_TRUNCATED_WRONG_VALUE,
     // so we get OB_INVALID_DATE_FORMAT / OB_INVALID_DATE_VALUE / OB_ERR_TRUNCATED_WRONG_VALUE.
     // another requirement comes from cast function in ob_obj_cast.cpp is this time object will be
@@ -5395,7 +5393,7 @@ int ObTimeConverter::time_overflow_trunc(int64_t &value, const ObScale &time_sca
     // so we get the ONLY one: OB_ERR_TRUNCATED_WRONG_VALUE, because the other two will direct to
     // ZERO_VAL of the temporal types, like cast 'abc' or '1998-76-54' to date.
     ret = OB_ERR_TRUNCATED_WRONG_VALUE;
-    value = TIME_MAX_VAL + increment;
+    value = TIME_MAX_VAL;
   }
   return ret;
 }
diff --git a/deps/oblib/src/lib/timezone/ob_time_convert.h b/deps/oblib/src/lib/timezone/ob_time_convert.h
index 1a4cc241b5..562561015e 100644
--- a/deps/oblib/src/lib/timezone/ob_time_convert.h
+++ b/deps/oblib/src/lib/timezone/ob_time_convert.h
@@ -157,7 +157,7 @@ extern const int64_t USECS_PER_MIN;
 #define MYSQL_TIMESTAMP_MIN_VAL -62167046400000000
 #define ORACLE_DATETIME_MIN_VAL -62135596800000000 //start from '0001-1-1 00:00:00'
 #define TIME_MAX_HOUR 838
-#define TIME_MAX_VAL (3020399 * 1000000LL)    // 838:59:59 .
+#define TIME_MAX_VAL (3020399 * 1000000LL)    // 838:59:59.
 
 struct ObIntervalLimit {
   static const ObOracleTimeLimiter YEAR;
@@ -408,8 +408,7 @@ public:
 
   static int str_is_date_format(const ObString &str, bool &date_flag);
   static int str_to_date(const ObString &str, int32_t &value, const ObDateSqlMode date_sql_mode = 0);
-  static int str_to_time(const ObString &str, int64_t &value, int16_t *scale = NULL,
-                         const ObScale &time_scale = 0, const bool &need_truncate = false);
+  static int str_to_time(const ObString &str, int64_t &value, int16_t *scale = NULL, const bool &need_truncate = false);
   static int str_to_year(const ObString &str, uint8_t &value);
   static int str_to_interval(const ObString &str, ObDateUnitType unit_type, int64_t &value);
   // int / double / string <- datetime(timestamp) / date / time / year.
diff --git a/src/share/object/ob_obj_cast.cpp b/src/share/object/ob_obj_cast.cpp
index d94381e25b..0b132e1328 100644
--- a/src/share/object/ob_obj_cast.cpp
+++ b/src/share/object/ob_obj_cast.cpp
@@ -5212,7 +5212,7 @@ static int string_time(const ObObjType expect_type, ObObjCastParams &params,
     ret = OB_NOT_SUPPORTED;
     LOG_ERROR("invalid use of blob type", K(ret), K(in), K(expect_type));
     LOG_USER_ERROR(OB_NOT_SUPPORTED, "Cast to blob type");
-  } else if (CAST_FAIL(ObTimeConverter::str_to_time(in.get_string(), value, &res_scale, 0, need_truncate))) {
+  } else if (CAST_FAIL(ObTimeConverter::str_to_time(in.get_string(), value, &res_scale, need_truncate))) {
   } else {
     SET_RES_TIME(out);
   }
@@ -12182,7 +12182,7 @@ int ob_obj_to_ob_time_without_date(const ObObj &obj, const ObTimeZoneInfo *tz_in
         LOG_WARN("int to ob time without date failed", K(ret));
       } else {
         //mysql中intTC转time时，如果hour超过838，那么time应该为null，而不是最大值。
-        const int64_t time_max_val = 3020399 * 1000000LL;    // 838:59:59 .
+        const int64_t time_max_val = TIME_MAX_VAL;    // 838:59:59 .
         int64_t value = ObTimeConverter::ob_time_to_time(ob_time);
         if (value > time_max_val) {
           ret = OB_INVALID_DATE_VALUE;
@@ -12218,6 +12218,14 @@ int ob_obj_to_ob_time_without_date(const ObObj &obj, const ObTimeZoneInfo *tz_in
     }
     case ObStringTC: {
       ret = ObTimeConverter::str_to_ob_time_without_date(obj.get_string(), ob_time);
+      if (OB_SUCC(ret)) {
+        int64_t value = ObTimeConverter::ob_time_to_time(ob_time);
+        int64_t tmp_value = value;
+        ObTimeConverter::time_overflow_trunc(value);
+        if (value != tmp_value) {
+          ObTimeConverter::time_to_ob_time(value, ob_time);
+        }
+      }
       break;
     }
     case ObLobTC: {
@@ -12230,13 +12238,25 @@ int ob_obj_to_ob_time_without_date(const ObObj &obj, const ObTimeZoneInfo *tz_in
       break;
     }
     case ObNumberTC: {
-      const char *num_format = obj.get_number().format();
-      if (OB_ISNULL(num_format)) {
-        ret = OB_ERR_UNEXPECTED;
-        LOG_WARN("number format value is null", K(ret));
+      int64_t int_part = 0;
+      int64_t dec_part = 0;
+      const number::ObNumber num(obj.get_number());
+      if (!num.is_int_parts_valid_int64(int_part, dec_part)) {
+        ret = OB_INVALID_DATE_FORMAT;
+        LOG_WARN("invalid date format", K(ret), K(num));
       } else {
-        ObString num_str(num_format);
-        ret = ObTimeConverter::str_to_ob_time_without_date(num_str, ob_time);
+        if (OB_FAIL(ObTimeConverter::int_to_ob_time_without_date(int_part, ob_time, dec_part))) {
+          LOG_WARN("int to ob time without date failed", K(ret));
+        } else {
+          if ((!ob_time.parts_[DT_YEAR]) && (!ob_time.parts_[DT_MON]) && (!ob_time.parts_[DT_MDAY])) {
+            //mysql中intTC转time时，如果超过838:59:59，那么time应该为null，而不是最大值。
+            const int64_t time_max_val = TIME_MAX_VAL;    // 838:59:59 .
+            int64_t value = ObTimeConverter::ob_time_to_time(ob_time);
+            if(value > time_max_val) {
+              ret = OB_INVALID_DATE_VALUE;
+            }
+          }
+        }
       }
       break;
     }
diff --git a/src/sql/engine/expr/ob_datum_cast.cpp b/src/sql/engine/expr/ob_datum_cast.cpp
index db9c2f7615..61a2710190 100644
--- a/src/sql/engine/expr/ob_datum_cast.cpp
+++ b/src/sql/engine/expr/ob_datum_cast.cpp
@@ -1051,11 +1051,10 @@ static OB_INLINE int common_string_time(const ObExpr &expr,
   int warning = OB_SUCCESS;
   int64_t out_val = 0;
   ObScale res_scale; // useless
-  ObScale time_scale = expr.datum_meta_.scale_;
   // support sqlmode TIME_TRUNCATE_FRACTIONAL
   const ObCastMode cast_mode = expr.extra_;
   bool need_truncate = CM_IS_COLUMN_CONVERT(cast_mode) ? CM_IS_TIME_TRUNCATE_FRACTIONAL(cast_mode) : false;
-  if (CAST_FAIL(ObTimeConverter::str_to_time(in_str, out_val, &res_scale, time_scale, need_truncate))) {
+  if (CAST_FAIL(ObTimeConverter::str_to_time(in_str, out_val, &res_scale, need_truncate))) {
     LOG_WARN("str_to_time failed", K(ret), K(in_str));
   } else {
     SET_RES_TIME(out_val);
@@ -11594,7 +11593,7 @@ int ob_datum_to_ob_time_without_date(const ObDatum &datum, const ObObjType type,
         LOG_WARN("int to ob time without date failed", K(ret));
       } else {
         //mysql中intTC转time时，如果hour超过838，那么time应该为null，而不是最大值。
-        const int64_t time_max_val = TIME_MAX_VAL;    // 838:59:59 .
+        const int64_t time_max_val = TIME_MAX_VAL;    // 838:59:59.
         int64_t value = ObTimeConverter::ob_time_to_time(ob_time);
         if (value > time_max_val) {
           ret = OB_INVALID_DATE_VALUE;
@@ -11656,8 +11655,8 @@ int ob_datum_to_ob_time_without_date(const ObDatum &datum, const ObObjType type,
           LOG_WARN("int to ob time without date failed", K(ret));
         } else {
           if ((!ob_time.parts_[DT_YEAR]) && (!ob_time.parts_[DT_MON]) && (!ob_time.parts_[DT_MDAY])) {
-            //mysql中intTC转time时，如果超过838:59:59.999999，那么time应该为null，而不是最大值。
-            const int64_t time_max_val = TIME_MAX_VAL + 999999;    // 838:59:59.999999 .
+            //mysql中intTC转time时，如果超过838:59:59，那么time应该为null，而不是最大值。
+            const int64_t time_max_val = TIME_MAX_VAL;    // 838:59:59.
             int64_t value = ObTimeConverter::ob_time_to_time(ob_time);
             if(value > time_max_val) {
               ret = OB_INVALID_DATE_VALUE;
diff --git a/unittest/sql/optimizer/ob_mock_stat_manager.h b/unittest/sql/optimizer/ob_mock_stat_manager.h
index f15288e180..007518e8ba 100644
--- a/unittest/sql/optimizer/ob_mock_stat_manager.h
+++ b/unittest/sql/optimizer/ob_mock_stat_manager.h
@@ -129,7 +129,7 @@ class MockStatManager : public oceanbase::common::ObStatManager
 {
   static const uint64_t DEFAULT_TABLE1_ID = 1099511677777;
   static const uint64_t DEFAULT_TABLE2_ID = 1099511677778;
-  static const int64_t TIME_MAX_VALUE = (3020399 * 1000000LL);
+  static const int64_t TIME_MAX_VALUE = TIME_MAX_VAL;
   static const int64_t DATE_MAX_VALUE = 2932896;
   static const int64_t DATE_MIN_VALUE = -354258;
 public: