The main clinical symptoms of children with AA are anemia, hemorrhage and recurrent infections, and simultaneous reduction of all three blood cell lines. Children with acute AA have the following characteristics: 1. The peripheral blood shows a decrease in whole blood cells, the absolute value of neutrophils, the percentage and absolute value of reticulocytes are significantly reduced, and the percentage of lymphocytes is significantly increased. There were no infantile cells in the peripheral blood. The bone marrow of the iliac bone and sternum showed hyperplasia in multiple parts, with a marked decrease in hematopoietic cells and a marked increase in non-hematopoietic cells, and a marked decrease in megakaryocytes, most of which were absent. The bone marrow of some children showed active proliferation, but the proportion of lymphocytes and other non-hematopoietic cells increased significantly, and the number of megakaryocytes decreased significantly. The liver, spleen and lymph nodes may be involved in repeated infections. The results of European bone marrow transplantation and international BMT registry show that the 2-year survival rates of HLA-identical sibling BMT and peripheral blood HSCT for AA are 80% and 7%, respectively. Only 20% of children with AA abroad can find a suitable sibling donor, and the chances are even lower in China. Therefore, some studies have tried to find other sources of donors, such as HLA-compatible non-related donors with bone marrow, peripheral hematopoietic stem cells or umbilical cord blood, or HLA-mismatched blood-related donors. With the continuous improvement of treatment protocols, the remission rate of SAA has been increased to 60%-80%, and the long-term survival rate and quality of survival have been improved. 2. Immunosuppressants such as ATG+CSA+MP are the more commonly used regimens for SAA. The time of efficacy response varies, about 1/2 occurring 3 months after treatment, and most starting 6 months after treatment. There is a rise in reticulocytes, followed by a rise in hemoglobin and leukocytes, and a slow recovery of platelets. The efficacy of haploidentical transplantation (found in almost all patients in children, such as their parents) is similar to that of HLA-identical sibling BMT. Our experience shows that haploidentical transplantation is faster than immunosuppressive therapy in children with hematopoietic and immune reconstitution, and that the transplantation process is safe, without serious complications, and well tolerated by children.