The main clinical symptoms of children with AA are anemia, bleeding and recurrent infections, and simultaneous reduction of all three blood cell lines. Acute AA in children has the following characteristics: 1. Peripheral blood shows a decrease in whole blood cells, with a significant decrease in the absolute value of neutrophils and the percentage and absolute value of reticulocytes, and a significant increase in the percentage of lymphocytes. There were no infantile cells in the peripheral blood. The bone marrow of the iliac bone and sternum showed multi-part hyperplasia, with a significant decrease in hematopoietic cells, a significant increase in non-hematopoietic cells, and a significant decrease in megakaryocytes, most of which were absent. 3. In some children, the bone marrow showed active proliferation, but the proportion of lymphocytes and other non-hematopoietic cells increased significantly, and megakaryocytes decreased significantly. 4.The liver, spleen and lymph nodes can be found in case of repeated infections . The results of European bone marrow transplantation (BMT) and international BMT registry show that the 2-year survival rates of HLA-compatible sibling BMT and peripheral blood HSCT for AA are 80% and 67%, respectively. Only 20% of children with AA abroad can find a suitable sibling donor, and the chances are even lower in China. We have recently developed other donor sources, such as peripheral HSCT from HLA-compatible non-blood-related donors and HLA-mismatched blood-related donors, which have achieved good results. Immunosuppressive therapy (IST), which is suitable for patients without suitable donors for HSCT SAA. The main drugs of IST are anti-thymocyte globulin (ATG), anti-lymphocyte globulin (ALG), cyclosporine (CSA), methylprednisolone (MP), and high-dose gammaglobulin (HD Ig). ATG +CSA+MP is the current standard regimen for SAA. The time to response varies, with about 1/2 occurring 3 months after treatment, and most taking effect 6 months after treatment. There is a rise in reticulocytes, followed by a rise in hemoglobin and leukocytes, and a slow recovery of platelets. In 25% of the cases not responding to immunosuppression, the child may respond to the second course of treatment.