The appearance of fever after leukemia bone marrow transplantation is associated with infection, rejection, and coagulation disorders. The appearance of fever after leukemia bone marrow transplantation is related to the following factors: 1. Infection: the damage of mucosal barrier, the use of immunosuppressant (tacrolimus), the application of central venous cannulation and other factors can cause a high incidence of opportunistic infections after bone marrow transplantation, and there may be infections when there is a high fever that doesn’t go away. 2. Rejection reaction: the body’s immune function will react to the bone marrow transplantation, and fever may appear when there is rejection reaction. 3. Coagulation dysfunction: Bone marrow transplantation can have certain effects on the coagulation function, thus causing fever. There may be other reasons for fever after leukemia bone marrow transplantation, it is recommended to go to the hospital in time, improve the examination to clarify the cause of the disease, and then give targeted treatment under the guidance of the physician or treatment.