Frequent fever is not necessarily leukemia, because fever is a very common and most difficult clinical symptom. There are various causes of fever, the most common being infectious diseases and non-infectious diseases such as connective tissue diseases and tumors. However, infection is the most common cause of fever, for example, common pneumonia and respiratory tract infection can cause fever. In common cold and fever, the patient’s immunity is normal, but in leukemia patients, the immunity is low, so the fever temperature in leukemia is relatively higher and this infection is more difficult to control. If there is frequent fever accompanied by other symptoms of leukemia, such as anemia, bleeding, epistaxis, skin petechiae, purpura and other bleeding conditions, and symptoms of anemia such as dizziness, weakness and pallor, and if there is then a higher fever, such as a body temperature of 38°C-39°C, be alert to the possibility of leukemia and seek prompt medical attention.