The diagnosis of aplastic anemia is confirmed by the following conditions: 1) allogeneic cytopenia; 2) there is usually no hepatosplenomegaly in aplasia; 3) determined by bone marrow image, i.e. bone marrow examination shows at least one site of hypoproliferation, or severe hypoplasia. If there is active hyperplasia, there must be a significant decrease in megakaryocytes and an increase in small non-hematopoietic cells in the bone marrow, and the diagnosis should be clarified with bone marrow biopsy if necessary; 4. Exclude other diseases that cause allogeneic cytopenia, such as common leukemia, myelofibrosis, myelodysplastic syndrome, paroxysmal sleep hemoglobinuria, and malignant histiocytosis; 5. Anti-anemia treatment is ineffective. Aplastic anemia can be diagnosed when these five conditions above are met.