Normal rectal temperature is 36.5-37.7℃, axillary temperature is 36℃ and oral sublingual temperature is 37℃. Body temperature is not fixed and can fluctuate normally with age, day and night, gender and emotional factors. Newborns have imperfect thermoregulatory functions and their body temperature is easily affected by environmental temperature. Children can have a slightly higher body temperature than adults due to their high metabolic rate, and older people have a low body temperature in the normal range due to their low metabolic rate. Normal human body temperature is lowest in the early morning at 2-6, and highest in the afternoon at 2-8, but the fluctuation range is no more than 0.5℃ above and below the average.