Myelodysplastic syndrome (MDS) is a group of heterogeneous clonal diseases originating from hematopoietic myeloid committed stem cells or pluripotent stem cells. Its basic pathology is clonal hematopoietic stem and progenitor cell dysplasia, which leads to ineffective hematopoiesis and increased risk of malignant transformation. The main characteristics are ineffective hematopoiesis and high risk of evolving into acute myeloid leukemia. The clinical manifestations are different degrees of abnormal changes in the quality and quantity of hematopoietic cells. The incidence of MDS is about 10/100,000 to 12/100,000 population, mostly affecting middle-aged and elderly people. Cases over 50 years old account for 50% to 70%, and the ratio of men to women is 2:1. 30% to 60% of MDS transform into leukemia. In addition to leukemia, most of the causes of death are due to infection and bleeding, especially intracranial hemorrhage.