Aplastic anemia (AA) is a bone marrow failure disorder characterized by complete blood cytopenia and low bone marrow proliferation. Clinical manifestations include anemia, infection and bleeding symptoms. Aplastic anemia is a bone marrow hematopoietic failure disease caused by multiple etiologies and pathogenesis. It is believed that abnormal activation and hyperfunction of T lymphocytes causing bone marrow damage (apoptosis) and failure play a major role in the pathogenesis of aplastic anemia, and this is supported by the effectiveness of immunosuppressive therapy in treating aplastic anemia. Diagnostic criteria: Diagnostic criteria for aplastic anemia: reduced whole blood cells, reticulocyte percentage <0.01, increased lymphocyte percentage; generally no liver or spleen enlargement; multiple sites of bone marrow hypoplasia (<50% of normal) or severe hypoplasia (<25% of normal), reduced hematopoietic cells, increased non-hematopoietic cell percentage, bone marrow granule vacuity; ④ except for other diseases that cause whole blood cell reduction. Patients with aplastic anemia can be diagnosed with SAA if they have ① absolute peripheral blood neutrophil (ANC) <0,5×109/L, ② reticulocytes <15×109/L, ③ platelet count <20×109/L, 2 of the 3 items; where ANC <0,2×109/L is diagnosed as very heavy aplastic anemia (VSAA). Treatment: Once the diagnosis of aplastic anemia is confirmed, the severity of the disease should be clarified and treated as early as possible. Currently, immunosuppressive therapy (IST) and sibling donor bone marrow transplantation (BMT) are included as standard therapies for remittent anemia. Due to the age limit and the difficulty in finding HLA compatible siblings for bone marrow transplantation, and with the continuous improvement of IST treatment, the efficiency of combined immunosuppressive therapy for reblastosis can be as high as 80%, thus making IST the main treatment for patients with aplastic anemia and the trend of replacing hematopoietic stem cell transplantation. ATG combined with CSA is the most important treatment method. 1.Treatment strategy for non-heavy reoccurrence: For non-heavy reoccurrence patients who do not depend on red blood cell and platelet transfusion, their peripheral blood picture should be monitored regularly, or they can be treated with hematopoietic (androgen, hematopoietic stimulating factor) alone for 3 months with no effect and CSA. if the disease progresses to blood product transfusion dependence, CSA combined with hematopoietic treatment or intensive IST (ATG+CSA) should be given immediately, and after After peripheral blood cells return to normal, CSA should be slowly reduced and maintained in small doses for 2-4 years to prevent disease recurrence. 2. Treatment strategy for SAA: The first-line treatment option for SAA is intensive IST (ATG+CSA) for patients with SAA or VSAA aged ≥40 years, and for patients with SAA or VSAA <40 years without a suitable sibling donor. Judgment of efficacy: The effectiveness of drug therapy in patients with aplastic anemia is first demonstrated by the prolongation of the time interval between transfusions of blood products; afterwards, bone marrow aspiration is repeated: the growth of bone marrow hematopoietic cells is restored, and the number of megakaryocytes gradually returns to normal from absent to present, from few to many; finally, the peripheral blood cells gradually return to normal, going through the process of "blood loss, long marrow, and long blood".