Abstract: Objective To explore the mechanism of the Taxus polysaccharide regulating immune function of immunosuppression mice. Methods Forty-eight male mice were randomly dividend into control group,model group,taxus polysaccharise group(low,medium and high does group) and positive control group.Mice in the control group were injected with 0.9% NaCl solution,other were injected with 0.2 mg/kg hydrocortisone every day for 14 days to establish the immunocompromised model.The control group and model group were with 200 mg/kg normal saline,three Taxus polysaccharide groups were treated with Taxus polysaccharide(100,200 and 400 mg/kg by body weight),one positive control group was treated with polysaccharide of hericium erinaceus.The cellular IL-2 and IFN-γ of mice was tested by Enzyme-linked immunoassay detection,The number of serum CD4⁺ and CD8⁺ were detected by flow cytometry. Results ①The serum of IL-2,IFN-γ in model group was significant lower as compared with control group(P<0.01),Compared with model group,the levels of IL-2 in the treatment groups were increased(P<0.01).Compared with model group,the serum of IFN-γ of the high,middle dose group had increased,with obvious significance in addition to the low dose group;②The number of CD4⁺T cells and CD8⁺T cells in model group were obviously reduced as compared with control group(P<0.05);The number of CD4⁺T cells and CD8⁺T cells in high-dose and middle-dose groups had obviously increased as compared with model group(P<0.01). Conclusion The mechanism of Taxus polysaccharide regulating the immune function in immunodepressed mice may associate with improvement immune function through regulating humoral immunity.