Children with low fever at night and normal during the day are related to children’s physiological rhythms. The causes of fever include physiological fever, external factors and other diseases, which are recommended to be dealt with promptly. I. Physiological factors are mostly caused by clothing, quilts too thick or ambient temperature is too high, baby metabolism is more vigorous, blood circulation is faster, the body produces more heat, clothing and quilt thickness can be moderate, generally no other discomfort. Second, disease factors child fever is mostly caused by infection, such as respiratory tract infection, digestive tract infection, urinary tract infection, etc., due to the inflammatory response and fever. With hyperthyroidism, it can cause endocrine and metabolic dysfunction, which is manifested by fever, sweating and irritability. Children are more active during the day, their immune system is more active, and their resistance to diseases and infections is relatively strong. After resting at night, their organism functions are weakened and they show symptoms such as fever. Treatment 1, daily care: cold compresses on the forehead or wipe the body with warm water can improve the symptoms of fever, timely increase and decrease clothing, dry sweat; 2, medication: it is recommended to use medication under the guidance of a doctor, such as taking pediatric antipyretic granules. If bacterial infection occurs, antibiotic treatment can be made. When sweating more, need to timely rehydration, such as oral rehydration salt.