According to lymphocyte morphology, acute lymphoblastic leukemia can be divided into three types, namely L1, L2 and L3, and it is not certain which type is the most serious, as it varies from person to person. The causes of acute lymphoblastic leukemia are complex, and may be related to heredity, environment and genetic changes, etc. Patients may suffer from anemia, infection and bleeding after the onset of the disease. 1. According to lymphocyte morphology, acute lymphoblastic leukemia can be divided into three types: L1, L2, and L3, of which L1 refers to the primitive lymphocyte type, which is mainly composed of small cells, with a diameter of about 12 μm or less, and is usually not particularly serious. 2. L2 is characterized by large cells, with a diameter of more than 12 μm, which can be cured after active treatment and is unlikely to produce sequelae. 3.L3 is mainly composed of large cells with high number and cytoplasm, with obvious vacuoles and honeycomb shape. Compared with L1 and L2, L3 is more serious and needs to be treated as soon as possible. Drugs include cyclophosphamide and vincristine. Patients are advised to go to the hospital for examination when abnormal symptoms occur, to learn about the typology of the disease as soon as possible, and to actively cooperate with the doctor’s treatment in order to control the development of the disease.