There are many reasons why children often have fever, such as low immunity, tuberculosis, leukemia and so on. 1. Low immunity: If a child’s immunity is low, he or she may be frequently invaded by viruses, leading to upper respiratory tract infections and recurrent fevers. 2. Tuberculosis: tuberculosis is caused by tuberculosis bacillus infection of the lungs, the onset of the immune system will be activated to fight inflammation, during which it is easy to show symptoms of recurrent fever. 3. Leukemia: Leukemia leads to hematopoietic dysfunction, reduction of normal white blood cells, and decreased ability to eliminate bacteria and viruses, resulting in frequent infections and recurrent fever. In addition, leukemia is a malignant tumor disease, so in the process of leukemia cell metabolism, it will also cause the problem of increased body temperature. There are many causes of recurrent fever in children, so parents and family members should not blindly treat the disease according to their own experience, but should go to the hospital in time.