Myelodysplastic syndrome, abbreviated as MDS, is a malignant clonal disorder of hematopoietic stem cells in which patients often have pathological hematopoiesis and a high risk of transformation to leukemia as clinical features. In the past, myelodysplastic syndrome was also known as pre-leukemia, commonly referred to as smoldering leukemia. Such patients often presented with a reduction in one, two, or three lines of peripheral blood and were sometimes easily confused with diseases such as aplastic anemia, paroxysmal sleep hemoglobinuria, and hemolytic anemia. The primary method to confirm the diagnosis of myelodysplastic syndrome is a bone marrow aspiration, which can reveal pathological hematopoiesis, and cytogenetic examination of the bone marrow, which often reveals complex karyotypic changes. Currently, the most promising cure for myelodysplastic syndrome is allogeneic hematopoietic stem cell transplantation, and demethylation therapy is the most conventional treatment.