Children’s constant fever may be caused by infections, immune function problems and other reasons. 1. Infection: If a child is infected by viruses or bacteria, he or she is likely to have digestive infections, respiratory infections, and so on, which will result in a constant fever. 2. Immune function problems: If a child has immune function problems such as low immune function, immune function defects, immune function deficiencies, or immune system disorders, he or she may have a constant fever. Fever in children may also be caused by malignant diseases such as tumors and blood system diseases, but the probability is usually low. There are many causes of fever in children, so parents are advised to take their children to the hospital for examination and correct and standardized treatment after clarifying the cause of the disease.