Lumbar puncture is not usually done for M3 leukemia, also known as acute promyelocytic leukemia, for the low and intermediate risk group. For the high-risk group M3 lumbar puncture and intrathecal injection are routinely done to prevent central leukemia. Acute promyelocytic leukemia (APL) is a special type of acute myeloid leukemia (AML) with aggressive clinical manifestations, and is prone to death caused by hemorrhage, embolism, and differentiation syndromes during onset and induction therapy. In low and intermediate patients, lumbar puncture is usually not performed; however, in the high-risk group M3, lumbar puncture and intrathecal injection are required to prevent central leukemia. Patients with APL usually also need to have routine blood tests, blood grouping, peripheral blood smear, biochemistry, DIC-related index test, bone marrow examination, immunophenotyping, molecular biology, cytogenetics, etc. to clarify the diagnosis and typing in order to adopt the appropriate chemotherapy regimen. Drugs include all-trans retinoic acid, arsenic trioxide, Zoerythromycin, and cytarabine. At present, through active treatment, the rate of complete remission of M3 is very high, and it is recommended that patients actively seek medical treatment and cooperate with physicians, which can effectively improve the prognosis.