A child’s temperature of 37.8°C is considered a fever. There are three ways to measure body temperature in human body, including axillary temperature, rectal temperature and oral sublingual temperature. 1. Axillary temperature: under normal circumstances, the temperature of the armpit should be between 36 ℃ and 37.2 ℃, if more than 37.3 ℃ is a fever. 2. Rectal temperature: under normal circumstances, it should be between 36.5℃~37.5℃, if it exceeds 37.6℃, it belongs to fever. 3. Oral sublingual temperature: the normal range of children’s oral temperature is 36.2℃~37.3℃, and exceeding 37.4℃ belongs to fever. Children’s temperature measurement is more commonly used axillary temperature, the child’s body temperature of 37.8 ℃, is a low fever, should pay close attention to the changes in body temperature, can be every half an hour for temperature testing, can also be used to use warm water baths and other physical cooling, and pay attention to the child’s mental state and whether there are other abnormal symptoms, if the body temperature continues to rise, or accompanied by other symptoms, it should be actively consult a doctor.