Myelodysplastic syndrome (MDS), formerly known as preleukemia, is a group of diseases that originate from damage at the hematopoietic stem/progenitor cell level. It lacks typical clinical manifestations, often with anemia, sometimes infection or bleeding, and some cases with hepatosplenomegaly. Blood pictures show pancytopenia or a decrease in any one or two lineage cells. The bone marrow proliferates actively, and there is significant morbid hematopoiesis in three or two lineages of blood cells. The course of the disease is slightly longer. If the patient does not die from infection or bleeding, it often develops into leukemia or bone marrow hematopoietic failure. The annual incidence of MDS in children is about 4.0/100,000, accounting for 9% of childhood blood tumors in the same period, which is similar to the incidence of AML in children.