Objective： To study the effect of double protein powder formed by the combination of soy protein isolate and whey protein on hematopoiesis and immune reconstitution in mice after allogeneic hematopoietic stem cell transplantation. Methods： Male BALB/c mice aged 6-8 weeks were randomly divided into normal control group （CON）， hematopoietic stem cell transplantation group （HSCT+NP）， and hematopoietic stem cell transplantation + protein intervention group （HSCT+PP）. Four weeks protein intervention experiment was performed after hematopoietic stem cell transplantation. HSCT+PP group was given a certain amount of double protein suspension， HSCT+NP group was given an equal volume of normal saline， and CON group without any treatment. The blood routine and mouse body weight of each group were measured weekly. The thymus and spleen indexes were measured at the 2nd and 4th week after transplantation， and the content of hematopoietic stem cells in bone marrow and serum biochemical parameters were determined at the time of the 4th week. Results： Compared with HSCT+NP group， the number of peripheral blood leukocytes， red blood cells， platelets and lymphocytes in the protein intervention group （HSCT+PP） recovered significantly faster （P<0.05）， and the bone marrow hematopoietic stem cell content was higher （P>0.05）， thymus index increased significantly （P<0.05）， serum total protein （TP）， immunoglobulin （IgG， IgA， IgM） content was higher， and IgM content was significantly increased （P<0.05）. Conclusion： the supplementation of double protein after hematopoietic stem cell transplantation can accelerate blood cell recovery and immune function reconstruction in mice. Thus， the double protein can be used as a good protein nutritional supplement after hematopoietic stem cell transplantation， which is beneficial to the prognosis of patients.