Babies with persistent fever of 38.1°C may have systemic or limited infections, juvenile-type connective tissue diseases, pediatric malignant tumors, endocrine diseases, etc., requiring further differential diagnosis. Infections, both systemic and limited, may cause persistent fever in children when present, such as tuberculosis, infective endocarditis, amoebic and bacillary dysentery, biliary tract infections, and appendicitis. Juvenile connective tissue diseases such as juvenile rheumatoid arthritis, systemic lupus erythematosus, polyarteritis nodosa, and dermatomyositis can cause persistent fever in young children. Pediatric malignant tumors such as lymphoma and various leukemias can cause persistent fever in young children. Endocrine disorders such as hyperthyroidism and pheochromocytoma can increase the pediatric body temperature and cause fever. Pediatric body temperature persistent 38.1 ℃ should be timely consultation, identify the cause of the disease, under the guidance of the doctor for treatment, daily attention to pediatric diet and hygiene, pay attention to keep warm, avoid cold.