Graft-versus-host disease (GVHD) is a major factor affecting the efficacy and quality of life of alternative donor transplantation in thalassemia major (TM), severely limiting the clinical application of alternative donor transplantation in TM.The purpose of this clinical trial is to evaluate whether recombinant humanized anti-CD25 monoclonal antibody is effective in preventing GVHD and its safety after haploidentical/matched unrelated donor hematopoietic stem cell transplantation. The main questions it aims to answer are: * Does recombinant humanized anti-CD25 monoclonal antibody reduce the incidence of GVHD disease after haploidentical/matched unrelated donor hematopoietic stem cell transplantation? * What medical problems will participants experience when using the recombinant humanized anti-CD25 monoclonal antibody? What is the quality of life after 2 years follow-up? In this clinical trail, participants will be randomly assigned to the intervention group or the control group by researchers in a 2:1 ratio. The intervention group will be given recombinant humanized anti-CD25 monoclonal antibody (1mg/Kg) combined with the standard GVHD prophylaxis after transplantation, while the control group will only receive the standard GVHD prophylaxis. The incidence of GVHD after transplantation in the two groups will be observed. The main evaluation is the clinical efficacy of recombinant humanized anti-CD25 monoclonal antibody in preventing aGVHD.