Abstract: Objective To investigate the effects of Arenaria Kansuensis aqueous extract(AKAE) on the immune function of H22 tumor-bearing mice. Methods Mice bearing H22 solid tumor were randomly divided into five groups: control group, cyclophosphamide(CTX) treatment group and three AKAE treatment groups (high, middle and low dosage). Each group was taken drug through administration by gavage for 10 days. After the mice were killed, the thymus and spleen were weighted respectively to calculate thymus and spleen indexes. The lymphocyte proliferation activity and CTL toxicity were detected by MTT method. The levels of IL-2 and IFN-γ in H22 tumor-bearing mice serum were detected by ELISA. Results After AKAE treatment, the thymus index were (21.39±14.3)mg/g, (17.52±7.7)mg/g, and (30.57±10.2)mg/g in the high, middle and low dosage AKAE group; the spleen index were (38.34±12.7)mg/g, (50.38±29.2)mg/g, and (61.63±35.2)mg/g, respectively. There was significant difference between CTX treatment groups and AKAE treatment groups. There was statistical difference between the low-dose AKAE group and control group(P=0.013). There was statistical difference in the stimulation index(SI) of spleen lymphocyte between high and low-dose AKAE groups(P=0.019). While, there was no significant difference in CTL killing activity among all groups. ELISA results showed that IL-2 expression in the high-dose AKAE group was higher than that in the control group, and IFN-γ expression in low-dose AKAE group was increased obviously compared with the control group(P=0.015). Conclusion AKAE could enhance the proliferation of spleen lymphocytes and promote Th1 cytokines expression in H22 tumor-bearing mice.