Although approximately 70% of pediatric hematological malignancies are curable, approximately 30% remain fatal. No standard treatment is available in patients showing relapse and those with refractory disease. Although different methods are adopted in different hospitals, its efficacy is extremely limited. In recent years, haploidentical stem cell transplantation, involving high-dose cyclophosphamide administration post-transplanta-tion, has been used, mainly in adults; however, its application is limited to removal of alloreactive T cells. Multicenter single-arm clinical trials of T-cell replete haploidentical stem cell transplantation (TCR-haplo-SCT) will be conducted in children with relapsed and refractory acute leukemia. After myeloablative conditioning using total body irradiation or busulfan, intensive graft versus host disease prophylaxis is administered, consisting of low-dose rabbit anti-human thymocyte globulin, tacrolimus, methotrexate, and prednisolone. An external control group is set up for the study. The treatment period is around 3 months, and the follow-up period is 2 years from transplantation completion. The aim of this study is to verify the efficacy and safety of TCR-haplo-SCT and present it as a new immune cell therapy for improving survival rate in children with relapsed and refractory acute leukemia.