Unexplained fever in children is mainly considered to be caused by infectious or non-infectious diseases. We need to take into account the specific situation of the child and the results of the examination to clarify the cause of the child’s fever, and then carry out targeted treatment. First, infectious diseases some due to infections caused by the disease can make children appear repeatedly fever, and fever lasts relatively long, mainly including respiratory infections, gastrointestinal infections and urinary tract infections and so on. It is recommended to consult a doctor in a timely manner to clarify the cause of the infection and give anti-infective treatment. 1, respiratory infections: common such as acute upper respiratory tract infections, bronchitis, bronchitis, pneumonia, etc., can lead to the early appearance of unexplained fever, which may also be accompanied by coughing, sore throat, poor mental health, and other symptoms; 2, gastrointestinal infections: for example, acute gastroenteritis, bacillary dysentery, etc., which can make the child appear unexplained fever, and may also be accompanied by a cough. 2, digestive system infections: such as acute gastroenteritis, bacterial dysentery, etc., can make children have an unknown fever, but also diarrhea, vomiting, abdominal pain and other symptoms; 3, urinary system infections: for example, acute nephritis, or urinary tract infections, fever may also be accompanied by frequent urination, urination and crying and other symptoms. Second, non-infectious diseases 1, rheumatic connective tissue disease: may be manifested as atypical rheumatoid or rheumatoid arthritis, there may also be systemic lupus erythematosus and so on, usually occurs throughout the body multi-system involvement. It is recommended to follow the doctor’s instructions for drug treatment or surgical treatment; 2, hematologic diseases: if long-term fever, we also need to pay attention to investigate whether the child’s blood system diseases, in the fever must be routine blood tests to see whether the child has anemia, as well as low hemoglobin, platelets, white blood cells, etc., a clear diagnosis to give the cause of the treatment.