To study Asparagus officinalis polysaccharide on the function of erythrocyte in S180 mice on immunological reaction of lymphocyte. Suspensions of lymphocytes and autologous plasma were separated from whole blood of healthy mice. The erythrocytes were separated from whole blood of Asparagus officinalis polysaccharide mice. Using the autologous plasm as reactive medium, the role of erythrocytes in regulating the immunological reaction of lymphocytes was mesured. The expression of CD25 on lymphocytes was measured by flow cytometry. The immunological regulating ability of erythrocyte in control group is much lower than normal group, and in Asparagus officinalis polysaccharide group is much higher than control group. According to the effects of erythrocyte CD35 on the immune-response of lymphocyte and the different of the expression of CD25 on lymphocytes, we prove that Asparagus officinalis polysaccharide can improve the erythrocyte function of S180 mice.