Myelodysplasia is mainly due to the abnormal hematopoietic function of bone marrow, which is manifested as anemia and recurrent infections, etc. Severe myelodysplasia can develop into leukemia, which is a pre-leukemia disease. 1. Myelodysplastic syndromes are mainly due to abnormal bone marrow hematopoietic function, which reduces the number of blood cells in the blood, manifesting as anemia, recurrent infections, and bleeding that is difficult to stop. Bone marrow cytology of patients with myelodysplastic syndromes shows that the number of primitive cells is less than 20%. 2. Leukemia is a class of malignant clonal disease of hematopoietic stem progenitor cells, which stagnates at different stages of cell development due to enhanced self-renewal of leukemic cells, uncontrolled proliferation, impaired differentiation, and blocked apoptosis. In the bone marrow and other hematopoietic tissues, leukemia cells proliferate and accumulate in large numbers, inhibiting normal hematopoiesis and infiltrating other organs and tissues. Bone marrow primitive cells in leukemia patients are mostly higher than 20%. In some special cases, although the bone marrow primitive cells are lower than 20%, when accompanied by leukemia-specific genetic or chromosomal changes, acute leukemia can be diagnosed instead of myelodysplastic syndromes. Some patients with myelodysplasia can eventually develop acute myeloid leukemia, and myelodysplasia is a pre-leukemic condition. Leukemia is a hematopoietic stem cell malignancy. The diagnosis of a specific disease should be made under the supervision of a physician.