Mild hypothermia during perioperative period is very common, and the percentage accounts for about half of all patients undergoing operations, which is directly related to the following three major adverse events that significantly increase their risks: 1) cardiac complications, 2) hemorrhage, 3) infection complications , particularly in patients with high risk factors (ASA grade III, IV). Furthermore, the decrease in body temperature may also lead to the following situations: 1) prolongation in retention time in post-anesthetic ICU (PACU), 2) decrease in the thermal comfort for patients, and thus affecting the satisfaction degree of patients and increasing cost.