Mixed leukemia, also known as heterozygous cell leukemia, is currently more difficult to cure. The concept, etiology and treatment are described below. 1. Heterogeneous leukemia refers to a group of acute leukemias in which both myeloid and lymphoid cell lines are involved. It can be divided into double-series type, i.e., the two groups of leukemia cells express the markers of myeloid and lymphoid lineages respectively; and double-phenotype, i.e., the same cell expresses the markers related to lymphoid and myeloid lineages at the same time. 2. The cause of leukemia is still unknown, but many factors are thought to be related to the development of leukemia, such as viruses, ionizing radiation, chemicals, and heredity. 3. There is no standard treatment plan for heterozygous leukemia. Currently, chemotherapy is the mainstay, with drugs including cytarabine, zithromax, cyclophosphamide, vincristine, etc. Allogeneic hematopoietic stem cell transplantation can be performed for severe symptoms, but the overall prognosis is poor. Although heterozygous leukemia cannot be cured at present, it can improve the quality of life and obtain long-term survival through active standardized treatment. Specific treatment and medication should be carried out under the guidance of physicians.