Hematopoietic stem cell transplantation (HSCT) is a treatment modality to achieve the therapeutic goal by pre-treating the transplant recipient with high-dose radiotherapy or other immunosuppressive agents to remove tumor cells and abnormal clonal cells from the recipient’s body and block the pathogenesis, and then transfusing autologous or allogeneic hematopoietic stem cells to the recipient to re-establish normal hematopoietic and immune functions in the body. Hematopoietic stem cell transplantation is now widely used in the treatment of malignant hematological diseases, non-malignant refractory hematological diseases, certain solid tumors, hereditary diseases, epidemic diseases and inborn metabolic diseases, and has achieved better efficacy. Huang Wenrong, Department of Hematology, Beijing 301 Hospital Hematopoietic stem cell transplantation is classified mainly according to the source of hematopoietic stem cells, immunogenetics and blood relationship: 1, according to the source of hematopoietic stem cells: bone marrow transplantation (BMT), peripheral blood stem cell transplantation (PBSCT) and umbilical cord blood stem cell transplantation (UCBT or UCBSCT); 2, immunological classification: autologous hematopoietic stem cell transplantation (HLA-compatible allogeneic HSCT), HLA-compatible allogeneic HSCT and HLA-mismatched allogeneic HSCT (e.g. HLA haplotype-compatible allogeneic HSCT), etc.; 3, classification according to blood relationship as hematologic HSCT and non-hematologic HSCT. Allogeneic bone marrow transplantation is a treatment method in which bone marrow from another person (excluding identical twins) is transplanted into the recipient’s body to grow and multiply and rebuild hematopoiesis and immunity. An allogeneic bone marrow transplant is one in which the recipient is genetically identical to the donor, and in humans, only between identical twins. Autologous bone marrow transplantation involves taking bone marrow cells from a leukemia patient in complete remission, pre-treating the patient with a curative dose of chemotherapy and/or total body irradiation (TBI) to kill as many residual leukemia cells as possible, and then returning the autologous bone marrow cells preserved in vitro to the patient via intravenous infusion to restore the bone marrow to its hematopoietic function for the purpose of curing leukemia. The process of mobilizing and releasing stem cells from the bone marrow into the peripheral blood by using different methods such as doing recombinant human granulocyte colony-stimulating factor (rhG-CSF), thereby harvesting stem cells directly from the blood and applying the harvested peripheral blood stem cells (PBSCs) for transplantation is known as peripheral blood stem cell transplantation (PBSCT). 1980 Rich et al. pioneered the process of transplanting stem cells from a child with severe combined immune In 1981, Korbing M et al. mobilized and collected enough peripheral blood stem cells from a patient with chronic granulocytic leukemia using cyclophosphamide, and the patient rapidly reestablished hematopoiesis after autologous peripheral blood stem cell transplantation, which pioneered the mobilization and collection of peripheral blood stem cells for transplantation. In 1989, Kessinger A et al. performed the first allogeneic peripheral blood HSCT in a patient with acute lymphoblastic leukemia after mobilizing donor peripheral blood stem cells with recombinant human granulocyte colony-stimulating factor, and the patient successfully completed donor-based hematopoietic reconstruction after transplantation. Coupled with the improved performance of cell separators, peripheral blood stem cell transplantation developed rapidly after 1989, and the Department of Hematology of the PLA General Hospital was the first to carry out peripheral blood hematopoietic stem cell transplantation for malignant hematologic diseases in China in 1989. Compared with bone marrow transplantation, the biggest advantage of peripheral blood stem cell transplantation is that a large number of hematopoietic stem cells can be collected, with fast hematopoietic recovery, no marrow harvesting for the donor, less painful and more acceptable, and fewer postoperative complications. According to the International Bone Marrow Transplant Registry, the number of peripheral blood stem cell transplants has exceeded the number of bone marrow transplants each year.