Three-year-old baby with a fever of 39 ℃, you can use physical cooling methods to solve the problem, you can give your baby a warm bath, the water temperature is controlled at about 2 ℃ lower than the body temperature, and the time of the warm bath should not be too long, you can also use a mixture of alcohol and water to wipe your baby’s forehead, armpits, groin and other parts of the body. You can also use some fever-reducing medications, including acetaminophen or ibuprofen granules, which can reduce fever. You can also go to the hospital to check the cause of the fever, whether it is infected with some microorganisms or some other reasons, and find out the cause of the fever so that it can be treated accordingly.