Abstract: In order to explore the effects of taxus polysaccharide on immune function in immunosuppressive mice induced by cyclophosphamide, in the experiment, 60 mice were randomly divided into negative control group, model group, positive drug group, low, medium and high dose groups of taxus polysaccharide, with 10 mice in each group. Mice in the model group, the positive drug group and the low, middle and high dose groups of taxus polysaccharide were intraperitoneally injected with cyclophospha mide solution at a weight of 80 mg/kg per day. Mice in the negative control group were injected with 0.01 mL/g of normal saline for 3 consecutive days to establish an immunosuppressive model. After the establishment of the model, the positive drug group was given levamisole hydrochloride solution by gavage at a weight of 10 mg/kg. The low, medium and high dose groups of taxus chinensis polysaccharide were respectively given 150 mg/kg, 300 mg/kg and 600 mg/kg of taxus chinensis polysaccharide solution by gavage, and the negative control group and the model group were given 0.01 mL/g of normal saline by gavage for 30 days. After the administration, the organ indexes（liver, spleen, thymus） of mice were measured. The levels of complement 3（C3）, complement 4（C4）, CD3 molecule（CD3）, CD4 molecule（CD4）, immunoglobulin A（IgA）, immunoglobulin G（IgG）, immunoglobulin M（IgM）, interleukin（IL）-2, and IL-4 in the serum of mice were detected by ELISA double antibody sandwich method. The results showed that intraperitoneal injection of cyclophosphamide successfully established a mouse immune suppression model. Compared with the negative control group, the immune organ index and serum C3, C4, CD3, CD4, IgA, IgG, IgM, IL-2 and IL-4 contents in the model group were significantly decreased（P＜0.01）. Compared with the model group, the immune organ index of each dose group of taxus polysaccharide significantly increased, and the effect of the high dose group of taxus polysaccharide was the most significant（P＜0.05 or P＜0.01）. Taxus polysaccharide could increase the serum C3, C4, CD3, CD4, IgA, IgG, IgM, IL-2, IL-4 levels of immunosuppressed mice, showing significant or extremely significant differences（P＜0.05 or P＜0.01）. These results indicated that taxus polysaccharide could improve the immune organ index and serum immune factor level in immunosuppressed mice, and played an immune enhancing role in immune organ, cellular immunity, humoral immunity and immune regulation.