The present study was designed to evaluate immune-modulating effects of the glycopeptide from Paecilomyces sinensis (CPS-II) by using mouse peritoneal macrophage and cytoxan (CTX) induced immunosuppression models. Our results from phagocytotic and mononuclear phagocytic system function assays showed that CPS-II stimulated phagocytosis of the phagocytes. A splenocyte proliferation assay showed that CPS-II acted to combine Concanavalin A (ConA) or lipopolysaccharides (LPS) in splenocyte proliferation. The results demonstrated that CPS-II increased the indices of the thymus and spleen. Hematological and histopathological analysis revealed the protective effect of CPS-II against CTX induced immunosuppression. CPS-II also significantly increased the expression of CD4(+) and CD8(+) splenic T lymphocytes, which were suppressed by CTX in peripheral blood. The expressions of serum cytokines related to immune function, including TNF-α, IL-6, and IFN-γ, were up-regulated in a dose-dependent manner. The expression of the transcription factor NF-κB in the spleen was enhanced after CPS-II-treatment. In conclusion, our results indicated that CPS-II was involved in immunostimulatory actions leading to its modulatory effects on immunosuppression, and one possible mechanism of action was to activate NF-κB.