A child’s constant fever may be related to the living environment, malnutrition, congenital heart disease, immunodeficiency diseases and so on. 1. Living environment: children’s fever may be caused by poor living environment. For example, if you often live in an environment with serious air pollution, or if someone in your family has a cold, the child’s resistance is poor, and inhaling such air for a long time will easily cause recurrent infections and lead to fever. 2. Malnutrition: Lack of nutrition is also the reason why children always have fever. If the child is malnourished, the child’s resistance will be lowered. In this way, the child will easily get infected and have recurrent fever. 3. Immunodeficiency diseases: The child’s constant fever is related to primary immunodeficiency diseases. For example, gammaglobulin deficiency. There may be other reasons for the child’s fever, it is recommended to go to the hospital in time, improve the examination to clarify the cause of the disease, and then give targeted treatment or treatment under the guidance of the doctor.