If your baby has a high fever of 40℃ and the fever does not go down for 3 days, it is recommended that you take your baby to the pediatrician of the hospital for blood tests and imaging tests to clarify the cause of the fever and treat the cause, and you should assist in lowering the temperature physically at the same time. When the baby has a fever, do not give the baby through too many clothes, cover a thick blanket, so as not to facilitate the dissipation of heat. At the same time should pay attention to let the baby drink more water, avoid dehydration at the same time also help dissipate heat. You can take warm water bath for physical cooling, reduce the baby’s body temperature. Can also be wrapped in ice packs outside the towel placed in the baby’s armpits, groin and other large blood vessels flow through the place, reduce body temperature, but should pay attention to the time should not be too long, every 20 minutes to change the part. In addition, you can take acetaminophen, ibuprofen and other drugs under the guidance of a doctor to reduce heat treatment, and should be alert to the occurrence of fever convulsions. If the fever is caused by a bacterial or viral infection, anti-inflammatory and anti-viral medications, etc., can be added as prescribed by the doctor. If mycoplasma infection is present, treatment with macrolides is indicated. If it is caused by a specific disease, the original disease needs to be actively treated according to the test results.