A 3-year-old child with a fever of 39 degrees needs to be reasonably antipyretic, while identifying the cause of the fever and treating it, such as children diagnosed with Kawasaki disease need to be treated with medications such as aspirin and gammaglobulin. For 3-year-old children, fever is a common symptom of the disease in this age group, when the baby appeared to have a significantly higher body temperature of 39 degrees, may appear mental depression, fatigue and other symptoms. At this time, the first need to actively and reasonably reduce fever, such as according to the baby’s weight to use ibuprofen or acetaminophen for medication to reduce fever, and discretionary with the use of antipyretic patches for physical cooling, etc.. At the same time, it is recommended to consult a doctor in time to find out the cause of fever and treatment, such as the above symptoms of the child, accompanied by chapped lips, skin rashes, or hard swelling of the hands and feet of the child, the diagnosis of Kawasaki disease is clear after the need for the use of gammaglobulin and aspirin and other medications to carry out the treatment. If caused by influenza, treatment with oseltamivir phosphate is required. There are many possible reasons for a 3 year old child to have a fever of 39 degrees, and it is recommended to actively seek medical attention to clarify the cause of the illness, and then be guided by a specialist. The medication should be taken in accordance with the doctor’s instructions.