Children’s immunity is weak and the thermoregulatory center is not well developed, so children’s fever is often caused by the following reasons: 1, high ambient temperature, excessive clothing, long-term malnutrition can lead to recurrent fever; 2, bacteria and viruses, their metabolites trigger endogenous substances in the body, which act on the thermoregulatory center to raise the body temperature, chlamydia, mycoplasma or parasites and other pathogens infection; 3, such as reactions after vaccination, allergic reactions, hyperthyroidism, tuberculosis, blood diseases such as leukemia, connective tissue diseases, etc. Recurrent fever can occur as a result of vaccination, allergic reactions, hyperthyroidism, tuberculosis, hematologic diseases such as leukemia, connective tissue diseases, etc. During the treatment of the disease, even if the condition improves or the fever subsides after taking antipyretic drugs, the fever can reappear or recur, so parents should take their children to the hospital for active examination and laboratory tests to identify the cause of the disease and eliminate the foci to control the fever, and if the fever is lower than 38.5℃, parents are advised to use physical cooling methods to reduce the harm of antipyretic drugs to the child’s body.