The normal body surface temperature of newborns is 36.0 to 36.5°C, and the normal core (rectal) temperature is 36.5 to 37.5°C. Neonatal thermoregulatory center function is not yet perfect, the subcutaneous fat is thin, the body surface area is relatively large, the skin epidermal keratinization layer is poor, easy to dissipate heat, especially in premature infants. There is no chilling response when cold but relies on brown fat chemical heat production. After birth, the ambient temperature is significantly lower than the intrauterine temperature, and heat dissipation increases. If not kept warm in time, hypothermia, hypoxemia, hypoglycemia and metabolic acidosis or cold injury can occur. In general, three sites are often used to measure body temperature, namely the oral cavity, axilla, and anus. Normal anal body temperature is 36.5 to 37.5°C, oral body temperature is 36.2 to 37.3°C, and body temperature at the axilla is 35.9 to 37.2°C. Infants generally have a body temperature over 37.3℃ as fever, and a body temperature below 36℃ as hypothermia. A body temperature above 37.3°C is recommended for infants under 5 months of age for physical cooling. For infants over 5 months of age with temperature over 38.5℃, antipyretic drugs are mostly recommended. For specific medication, please combine with the clinical situation and be guided by the doctor’s face-to-face consultation. physical cooling such as drinking water and warm water bath is recommended below 38.5℃. Newborn babies, especially premature babies, will have poor thermoregulatory function and immature development of thermoregulatory center, which will cause hypothermia or fever when the environmental temperature changes more than the baby’s own thermoregulatory ability.