Allogeneic hematopoietic stem cell transplantation is an important treatment method for NK-T cell lymphoma, but the recurrence rate after transplantation is relatively high. Therefore, exploring efficient and low-toxicity maintenance treatment strategies after transplantation is a key challenge for improving prognosis. Previous studies have reported that selinexor and azacitidine show good anti-tumor activity in relapsed/refractory NKTCL. Thus, we conducted a single-center, single-arm, exploratory study on the efficacy and safety of selinexor combined with azacitidine as maintenance therapy after allogeneic hematopoietic stem cell transplantation for NK/T cell lymphoma, to evaluate the efficacy and safety of the combined regimen, with the aim of providing reference for clinical treatment.