Fever is medically known as a fever. The main causes of fever in leukemia patients are various infections, and leukemia itself can also cause fever. Fever in leukemia patients is persistent and low in the early stages and high in the later stages, but it is not possible to determine whether a patient has leukemia by fever alone. Patients are advised to undergo early examination and treatment if they develop high fever or frequent low-grade fever to facilitate identification of the disease. Among the early symptoms of leukemia, most of these patients present with fever below 38°C in the early stage and high fever of 39°C or 40°C in the late stage of continuous disease development, mostly with recurrent irregular fever. In addition to fever, patients with leukemia also present with other physical symptoms such as nasal congestion, cough, sputum, runny nose and other respiratory infections or lung infections as well as anemia. When peripheral blood tests for routine blood work are done, typical blood abnormalities such as anemia, thrombocytopenia and changes in white blood cell count and white blood cell quality are seen. The treatment of leukemia fever needs to be carried out according to different situations, mainly as follows: 1. drug reactions during radiotherapy: for this type of fever simply take antipyretic drugs; 2. fever caused by inflammatory infections: corresponding antibiotic drugs need to be taken for the infection factors; 3. fever caused by low white blood cells: we should do heat treatment first, and then improve the quality of white blood cells and kill the leukemia cells.