The causes of low fever in a child as soon as the afternoon includes tuberculosis, other infectious diseases, immune diseases and so on. 1. Tuberculosis: Tuberculosis often manifests itself as recurrent low-grade fever, accompanied by coughing, coughing up sputum, night sweats (sweating abnormally after going to sleep and stopping sweating after waking up), and emaciation, etc., which need to be clarified by perfecting the chest radiographs, sputum smears, and tuberculin tests. 2. Other infectious diseases: Bacterial, viral and mycoplasma infections may cause recurrent fever, and the duration and degree of fever varies according to the individual’s condition and the severity of the infection, so parents need to reduce the clothing, lower the room temperature, and warm water baths. 3. Immune diseases: systemic lupus erythematosus may cause recurrent fever, accompanied by skin rashes, skin hemorrhages, joint pain and other symptoms, and need to improve the immunological examination to clarify. Children have a low fever in the afternoon, there may be other reasons, it is recommended to go to the hospital in a timely manner, improve the examination to determine the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.