The objectives of this study were to investigate the immune enhancement activity of the Sarcodon imbricatus polysaccharide (SIP). In this study, water extraction method was employed to isolate polysaccharides from the Sarcodon imbricatus. The immunoloregulation effects of SIP were evaluated with models of cyclophosphamideinduced mouse immunosuppression. The immunoloregulation activities of SIP were investigated using T lymphocyte subpopulation assays. The ability of these polysaccharides to stimulate mouse cytokine and splenocyte proliferation were measured using ELISA test and MTT reagent. The results revealed that SIP could significantly increase CD3+% and decrease CD4+/CD8+ with dose-dependent in vivo. In serum, IL-2 and IFN-γ content were raised after the immunosuppressive mouse were treated by SIP, meanwhile the serum IL-4 content was decreased. SIP also significantly promoted splenocyte proliferation. The immunoenhancement activities of SIP was better than astragalus polysaccharides (APS) with same dose. Outcomes of this research strongly indicate that SIP display significant immunoenhancement activities to immunosuppressive mouse, and have therapeutic potential to be used for the treatment of immunosuppressive disease.