First, monitor the child’s temperature for fever. The most common causes of fever can be divided into two categories: first, infectious fever, such as bacteria, viruses, fungi, mycoplasma, legionella and other atypical pathogens, HIV, gonorrhea and so on. Among them, fever caused by bacterial infection is the most common. Next to viral, non-infectious fevers, the first category, blood diseases, such as leukemia, lymphoma. The second category, tumor-related diseases. For example, malignant histiocytoma, as well as primary hepatocellular carcinoma and malignant lymphoma. In addition, rheumatic immune diseases, such as systemic lupus erythematosus, dermatomyositis, arteritis, and connective tissue disease. Functional fever, hyperthyroidism, heat stroke, massive burns, cranio-cerebral trauma, and drug fever. It is recommended to go to the fever clinic or the respiratory department for further relevant examinations, such as chest CT, blood tests, C-reactive protein, anti-nuclear antibodies, and autoimmune antibodies, to clarify the cause.