Babies with repeated high fever of 39 degrees for 4 days are mostly caused by pathogenic bacterial infections. Continue to observe the temperature, and if it still does not subside for more than 10 days, perform a bone marrow aspiration to exclude non-infectious factors such as hematologic diseases that cause it. Need to promptly go to the hospital for examination, after clarifying the cause, symptomatic treatment. Common causes 1, infectious factors: often due to influenza virus, herpes virus, bacteria, mycoplasma, chlamydia and other infections cause fever, mostly seen in the upper and lower respiratory tract infections, urinary system, intracranial infections. To go to the hospital for careful examination, blood and urine testing, if necessary, to take a chest X-ray, the diagnosis is clear to take the appropriate treatment; 2, non-infectious fever: continue to observe the temperature, if it still does not recede, more than 10 days, to perform a bone marrow aspiration to exclude blood system diseases, to exclude non-infectious factors caused by. Treatment measures 1, medication: can be under the guidance of professional doctors, oral acetaminophen, ibuprofen suspension mix and other antipyretic drugs, or the use of pediatric antipyretic suppositories. In case of influenza virus infection, oral oseltamivir can be taken under the guidance of a doctor, herpes virus infection can be treated with interferon, mycoplasma, chlamydia infection can be treated with azithromycin and other medications; 2. Physical therapy: such as the use of pediatric antipyretic patch, need to ice the groin, armpits and other large blood vessels, and loosen the clothes, etc. Attention in the physical cooling, should pay attention to ice to avoid baby frostbite, should also pay attention to keep warm, but also need to be alert to the high temperature and febrile convulsions caused by high.