I. Diagnostic criteria of aplastic anemia: 1. Decreased whole blood cells and decreased absolute value of reticulocytes. 2.Usually no splenomegaly. 3.Bone marrow examination shows at least part of hypoplasia or severe hypoplasia (if proliferation is active, there must be a decrease in megakaryocytes, and an increase in non-hematopoietic cells should be seen in the small granular component of bone marrow, and bone marrow biopsy should be performed if available). 4.It is possible to exclude other diseases that cause complete blood cell reduction, such as paroxysmal sleep erythropoietic proteinuria, refractory anemia in myelodysplastic syndrome, acute hematopoietic arrest, myelofibrosis, acute leukemia, malignant histiocytosis, etc. 5. General anti-anemia drug treatment is ineffective. Acute aplastic anemia is also known as heavy aplastic anemia type I. Diagnostic criteria: 1. Clinical: acute onset, progressive increase in anemia, often accompanied by severe infection and internal bleeding. 2.Blood picture: In addition to the rapid decline of hemoglobin, two of the following three items must be present: reticulocytes <1%, absolute value <0.015×1012/L (<15,000/ul); leukocytes significantly reduced, absolute value of neutrophils <0.5×109/L (<500/ul); platelets <20×109/L (<10-20,000/ul). 3. Bone marrow picture: decreased hyperplasia at multiple sites, marked decrease in hematopoietic cells of three lineages, increase in non-hematopoietic cells, such as active hyperplasia with increased lymphocytes; increased bone marrow small granular non-hematopoietic cells and adipocytes. Chronic aplastic anemia diagnostic criteria: 1, clinical: slow onset, anemia, infection, light bleeding. 2. Blood picture: hemoglobin decreases slowly, reticulocytes, leukocytes, neutrophils and platelets are higher than those of acute aplastic anemia. 3. Bone marrow picture: three or two lineages are reduced, at least one part is poorly proliferated, if the proliferation is good, the proportion of late juvenile red (charcoal nuclei) in the red lineage is often increased and megakaryocytes are reduced; the bone marrow small granular fat cells and non-hematopoietic cells are increased. 4. If the disease deteriorates during the course of the disease, the clinical blood and bone marrow picture is the same as that of acute aplastic anemia, it is called heavy aplastic anemia type II.