The efficacy of CAR-T cell therapy for refractory relapsed acute B-lymphocytic leukemia is remarkable, with very high remission rates (70%-90%) and deep remission to negative minimal residual disease (MRD). To prevent relapse, allogeneic hematopoietic stem cell transplantation (allo-HSCT) is recommended as soon as possible after disease remission with CAR-T cell therapy, provided the patient has a suitable donor and is medically eligible for transplantation.