Leukemia patients do lumbar puncture for the following reasons: 1, the need for disease diagnosis: leukemia is a class of hematopoietic stem cell malignant clonal disease, leukemia cells from the bone marrow, while the leukemia cells inside the bone marrow can pass through the peripheral blood, into the various organs of the body, when the infiltration to the meninges, infiltration to the central nervous system, you can help diagnose through lumbar puncture, plus clinical symptoms CNS leukemia; 2. Need for disease treatment: Intrathecal injection through lumbar puncture to treat CNS leukemia by injecting chemotherapeutic drugs such as methotrexate, dexamethasone, and cytarabine into the cerebrospinal fluid. 3. Prevention of central leukemia: Certain leukemias, such as acute lymphoblastic leukemia, are very prone to invade the center and therefore require lumbar puncture for intrathecal chemotherapy Drugs to prevent the occurrence of central leukemia.