Abstract: Objective:To study the immunomodulatory effect of white Hypsizygus marmoreus on spleen and thymus of immunosuppressed mice. Methods:Ultrasonic assisted hot water extraction and sevage method to remove protein and obtain white polysaccharides. The mice were randomly divided into a blank control group,a model control group,a positive control group,a low dose group of RPHM(30 mg/kg bw/d),a medium dose group of RPHM(60 mg/kg bw/d),and a high dose group of RPHM.(120 mg/kg bw/d),intragastric administration at the same time every day to establish an immunosuppressive mouse model,15 days of gavage. The spleen and thymus of the mice were taken,and their body weight and organ index were measured. Serum cytokines and monocyte-macrophage phagocytosis ability;peripheral leukocytes,red blood cells and platelets were counted and the morphology of spleen and thymus were observed. Results:Compared with the model group the middle and high dose groups of RPHM,the hair color,activity,body condition,appetite,body weight,spleen index and thymus index,mononuclear-macrophage phagocytosis and bone marrow hematopoietic function of immunosuppressed mice were significantly improved. It can also increase the levels of IL-2,IL-12,IFN-γ and TNF-α in immunosuppressive mice to acertain extent,and improve the abnormal secretion of IL-6;it can also significantly improve the spleen of immunosuppressed mice,thymic lesions,improve structural integrity.Conclusion:RPHM has obvious protective effects on spleen and thymus of immunosuppressed mice.