There are many causes of fever in babies, such as infectious factors, non-infectious factors and environmental factors. 1. Infectious factors: various pathogens such as bacteria, mycoplasma, viruses, etc., caused by various systems such as the respiratory system, digestive system, or the urinary system and other infections, will lead to the baby’s temperature center disorders, which will cause the baby fever. 2. Non-infectious factors: non-infectious factors cause fever in babies, such as Kawasaki disease of connective tissue disease, leukemia or lymphoma of oncological diseases, etc., which can cause the baby’s body temperature to rise. 3. Environmental factors: the baby’s thermoregulatory center is not yet fully developed, such as wearing too many clothes, or the surrounding environment is too high temperature, the baby can not dissipate heat in a timely manner, may cause the baby to have a fever, but usually for low fever. Baby fever may also have other reasons, it is recommended to go to the hospital in a timely manner, improve the examination to clarify the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.