diff --git a/src/observer/ob_server.cpp b/src/observer/ob_server.cpp
index 52575eee2..b530bc987 100644
--- a/src/observer/ob_server.cpp
+++ b/src/observer/ob_server.cpp
@@ -154,6 +154,7 @@ ObServer::ObServer()
     bandwidth_throttle_(),
     sys_bkgd_net_percentage_(0),
     ethernet_speed_(0),
+    cpu_frequency_(DEFAULT_CPU_FREQUENCY),
     session_mgr_(),
     root_service_monitor_(root_service_, rs_mgr_),
     ob_service_(gctx_),
@@ -171,6 +172,7 @@ ObServer::ObServer()
     ctas_clean_up_task_(),
     refresh_active_time_task_(),
     refresh_network_speed_task_(),
+    refresh_cpu_frequency_task_(),
     schema_status_proxy_(sql_proxy_),
     is_log_dir_empty_(false),
     conn_res_mgr_(),
@@ -373,6 +375,8 @@ int ObServer::init(const ObServerOptions &opts, const ObPLogWriterCfg &log_cfg)
       LOG_ERROR("init refresh active time task failed", KR(ret));
     } else if (OB_FAIL(init_refresh_network_speed_task())) {
       LOG_ERROR("init refresh network speed task failed", KR(ret));
+    } else if (OB_FAIL(init_refresh_cpu_frequency())) {
+      LOG_ERROR("init refresh cpu frequency failed", KR(ret));
     } else if (OB_FAIL(init_collect_info_gc_task())) {
       LOG_ERROR("init collect info gc task failed", KR(ret));
     } else if (OB_FAIL(ObOptStatManager::get_instance().init(
@@ -2787,6 +2791,63 @@ void ObServer::ObRefreshNetworkSpeedTask::runTimerTask()
   }
 }
 
+ObServer::ObRefreshCpuFreqTimeTask::ObRefreshCpuFreqTimeTask()
+: obs_(nullptr), is_inited_(false)
+{}
+
+int ObServer::ObRefreshCpuFreqTimeTask::init(ObServer *obs, int tg_id)
+{
+  int ret = OB_SUCCESS;
+  if (OB_UNLIKELY(is_inited_)) {
+    ret = OB_INIT_TWICE;
+    LOG_ERROR("ObRefreshCpuFreqTimeTask has already been inited", KR(ret));
+  } else if (OB_ISNULL(obs)) {
+    ret = OB_ERR_UNEXPECTED;
+    LOG_ERROR("ObRefreshCpuFreqTimeTask init with null ptr", KR(ret), K(obs));
+  } else {
+    obs_ = obs;
+    is_inited_ = true;
+    if (OB_FAIL(TG_SCHEDULE(tg_id, *this, REFRESH_INTERVAL, true /*schedule repeatly*/))) {
+      LOG_ERROR("fail to schedule task ObRefreshCpuFreqTimeTask", KR(ret));
+    }
+  }
+  return ret;
+}
+
+void ObServer::ObRefreshCpuFreqTimeTask::destroy()
+{
+  is_inited_ = false;
+  obs_ = nullptr;
+}
+
+void ObServer::ObRefreshCpuFreqTimeTask::runTimerTask()
+{
+  int ret = OB_SUCCESS;
+  if (OB_UNLIKELY(!is_inited_)) {
+    ret = OB_NOT_INIT;
+    LOG_ERROR("ObRefreshCpuFreqTimeTask has not been inited", KR(ret));
+  } else if (OB_ISNULL(obs_)) {
+    ret = OB_ERR_UNEXPECTED;
+    LOG_ERROR("ObRefreshCpuFreqTimeTask task got null ptr", KR(ret));
+  } else if (OB_FAIL(obs_->refresh_cpu_frequency())) {
+    LOG_ERROR("ObRefreshCpuFreqTimeTask task failed", KR(ret));
+  }
+}
+
+int ObServer::refresh_cpu_frequency()
+{
+  int ret = OB_SUCCESS;
+  uint64_t cpu_frequency = get_cpufreq_khz();
+
+  cpu_frequency = cpu_frequency < 1 ? 1 : cpu_frequency;
+  if (cpu_frequency != cpu_frequency_) {
+    LOG_INFO("Cpu frequency changed", "from", cpu_frequency_, "to", cpu_frequency);
+    cpu_frequency_ = cpu_frequency;
+  }
+
+  return ret;
+}
+
 void ObServer::ObCollectInfoGCTask::runTimerTask()
 {
   int ret = OB_SUCCESS;
@@ -2867,6 +2928,15 @@ int ObServer::init_refresh_network_speed_task()
   return ret;
 }
 
+int ObServer::init_refresh_cpu_frequency()
+{
+  int ret = OB_SUCCESS;
+  if (OB_FAIL(refresh_cpu_frequency_task_.init(this, lib::TGDefIDs::ServerGTimer))) {
+    LOG_ERROR("fail to init refresh cpu frequency task", KR(ret));
+  }
+  return ret;
+}
+
 int ObServer::init_collect_info_gc_task()
 {
   int ret = OB_SUCCESS;
diff --git a/src/observer/ob_server.h b/src/observer/ob_server.h
index 32d4848f7..edd6c90aa 100644
--- a/src/observer/ob_server.h
+++ b/src/observer/ob_server.h
@@ -99,6 +99,7 @@ class ObServer
 public:
   static const int64_t DEFAULT_ETHERNET_SPEED = 1000 / 8 * 1024 * 1024; // default 125m/s  1000Mbit
   static const int64_t DISK_USAGE_REPORT_INTERVAL = 1000L * 1000L * 10L; // 60s
+  static const uint64_t DEFAULT_CPU_FREQUENCY = 2500 * 1000; // 2500 * 1000 khz
   static ObServer &get_instance();
 
 public:
@@ -158,6 +159,20 @@ public:
     bool is_inited_;
   };
 
+  class ObRefreshCpuFreqTimeTask: public common::ObTimerTask
+  {
+  public:
+    ObRefreshCpuFreqTimeTask();
+    virtual ~ObRefreshCpuFreqTimeTask() {}
+    int init(ObServer *observer, int tg_id);
+    void destroy();
+    virtual void runTimerTask() override;
+  private:
+    const static int64_t REFRESH_INTERVAL = 10 * 1000L * 1000L;//10s
+    ObServer *obs_;
+    bool is_inited_;
+  };
+
   class ObCollectInfoGCTask : public common::ObTimerTask
   {
   public:
@@ -208,6 +223,7 @@ public:
   };
   share::schema::ObMultiVersionSchemaService &get_schema_service() { return schema_service_; }
   ObInOutBandwidthThrottle &get_bandwidth_throttle() { return bandwidth_throttle_; }
+  uint64_t get_cpu_frequency_khz() { return cpu_frequency_; }
   const common::ObAddr &get_self() const { return self_addr_; }
   const ObGlobalContext &get_gctx() const { return gctx_; }
   ObGlobalContext &get_gctx() { return gctx_; }
@@ -267,6 +283,7 @@ private:
   int get_network_speed_from_sysfs(int64_t &network_speed);
   int get_network_speed_from_config_file(int64_t &network_speed);
   int refresh_network_speed();
+  int refresh_cpu_frequency();
   int clean_up_invalid_tables();
   int clean_up_invalid_tables_by_tenant(const uint64_t tenant_id);
   int init_ctas_clean_up_task(); //Regularly clean up the residuals related to querying and building tables and temporary tables
@@ -275,6 +292,7 @@ private:
   int refresh_temp_table_sess_active_time();
   int init_refresh_active_time_task(); //Regularly update the sess_active_time of the temporary table created by the proxy connection sess
   int init_refresh_network_speed_task();
+  int init_refresh_cpu_frequency();
   int init_collect_info_gc_task();
   int set_running_mode();
   int check_server_can_start_service();
@@ -366,6 +384,7 @@ private:
   common::ObInOutBandwidthThrottle bandwidth_throttle_;
   int64_t sys_bkgd_net_percentage_;
   int64_t ethernet_speed_;
+  uint64_t cpu_frequency_;
 
   // sql session_mgr
   sql::ObSQLSessionMgr session_mgr_;
@@ -414,6 +433,7 @@ private:
   ObRedefTableHeartBeatTask redef_table_heart_beat_task_;
   ObRefreshTimeTask refresh_active_time_task_; // repeat & no retry
   ObRefreshNetworkSpeedTask refresh_network_speed_task_; // repeat & no retry
+  ObRefreshCpuFreqTimeTask refresh_cpu_frequency_task_;
   ObCollectInfoGCTask collect_info_gc_task_;
   blocksstable::ObStorageEnv storage_env_;
   share::ObSchemaStatusProxy schema_status_proxy_;
diff --git a/src/sql/engine/ob_operator.cpp b/src/sql/engine/ob_operator.cpp
index efb7a4d60..a8c8c397c 100644
--- a/src/sql/engine/ob_operator.cpp
+++ b/src/sql/engine/ob_operator.cpp
@@ -18,6 +18,7 @@
 #include "sql/engine/ob_exec_context.h"
 #include "common/ob_smart_call.h"
 #include "sql/monitor/ob_sql_plan_manager.h"
+#include "observer/ob_server.h"
 
 namespace oceanbase
 {
@@ -937,7 +938,10 @@ int ObOperator::submit_op_monitor_node()
           }
         }
         // exclude io time cost
-        op_monitor_info_.db_time_ = db_time;
+        uint64_t cpu_khz = OBSERVER.get_cpu_frequency_khz();
+        op_monitor_info_.db_time_ = 1000 * db_time / cpu_khz;
+        op_monitor_info_.block_time_ = 1000 * op_monitor_info_.block_time_ / cpu_khz;
+
         IGNORE_RETURN list->submit_node(op_monitor_info_);
         LOG_DEBUG("debug monitor", K(spec_.id_));
       }
diff --git a/src/sql/engine/px/exchange/ob_px_transmit_op.cpp b/src/sql/engine/px/exchange/ob_px_transmit_op.cpp
index 3098d34a1..711ace0ce 100644
--- a/src/sql/engine/px/exchange/ob_px_transmit_op.cpp
+++ b/src/sql/engine/px/exchange/ob_px_transmit_op.cpp
@@ -575,7 +575,6 @@ int ObPxTransmitOp::send_rows_one_by_one(ObSliceIdxCalc &slice_calc)
         } else if (OB_FAIL(send_eof_row())) { // overwrite err code
           LOG_WARN("fail send eof rows to channels", K(ret));
         }
-        op_monitor_info_.db_time_ += (rdtsc() - begin_cpu_time);
         break;
       }
     }
@@ -604,7 +603,6 @@ int ObPxTransmitOp::send_rows_one_by_one(ObSliceIdxCalc &slice_calc)
         }
       }
     }
-    op_monitor_info_.db_time_ += (rdtsc() - begin_cpu_time);
   }
   if (OB_ITER_END == ret) {
     ret = OB_SUCCESS;
@@ -721,11 +719,9 @@ int ObPxTransmitOp::send_rows_in_batch(ObSliceIdxCalc &slice_calc)
       } else if (OB_FAIL(send_eof_row())) {
         LOG_WARN("fail send eof rows to channels", K(ret));
       }
-      op_monitor_info_.db_time_ += (rdtsc() - begin_cpu_time);
       break;
     }
     // for those break out ops
-    op_monitor_info_.db_time_ += (rdtsc() - begin_cpu_time);
   }
   LOG_TRACE("Transmit time record", K(row_count), K(ret));
   return ret;
diff --git a/src/sql/monitor/ob_plan_info_manager.cpp b/src/sql/monitor/ob_plan_info_manager.cpp
index 48182196e..9ad17d482 100644
--- a/src/sql/monitor/ob_plan_info_manager.cpp
+++ b/src/sql/monitor/ob_plan_info_manager.cpp
@@ -14,6 +14,7 @@
 #include "lib/ob_running_mode.h"
 #include "util/easy_time.h"
 #include "lib/rc/ob_rc.h"
+#include "observer/ob_server.h"
 
 namespace oceanbase
 {
@@ -132,8 +133,7 @@ int ObPlanRealInfoMgr::handle_plan_info(int64_t id,
         SERVER_LOG(WARN, "alloc mem failed", K(total_size), K(ret));
       }
     } else {
-      uint64_t cpu_khz = get_cpufreq_khz();
-      cpu_khz = cpu_khz < 1 ? 1 : cpu_khz;
+      uint64_t cpu_khz = OBSERVER.get_cpu_frequency_khz();
       int64_t row_count = plan_info.output_row_count_;
       int64_t cpu_time = plan_info.db_time_*1000 / cpu_khz;
       int64_t io_time = plan_info.block_time_*1000 / cpu_khz;