Objective To study the immunoregulatory activity in vivo and in vitro and the preliminary pharmacological mechanism of the polysaccharide XP-10 isolated from Aconiturn brachypodum Diels, so as to provide scientific basis for the application and rational development of the polysaccharide from Aconiturn brachypodum Diels. Methods To construct an in vitro mouse splenic lymphocyte model, ConA, LPS, and anti CD3 antibodies were used to induce splenic lymphocyte proliferation, and MTT assay was used to detect the viability of splenic lymphocytes in each group; ELISA method was used to detect the levels of cytokines IFN-γ, IL-2, and IL-6 in the supernatant of ConA induced splenic lymphocyte culture. The immunosuppression model in vivo induced by cyclophosphamide was constructed, and the effect of XP-10 on the immune organ index of model mice was measured; MTT assay was used to detect the viability level of splenic lymphocytes in each group; Flow cytometry was used to detect the expression level of Treg cells(CD4+ Foxp3+ ) in spleen lymphocytes of each group. Splenic lymphocyte cell viability was measured using MTT assay. The levels of IFN-γ, IL-2 and IL-6 in the supernatant induced by ConA were detected by ELISA. Mice were injected with the immunosuppressant cyclophosphamide(CTX, 80 mg/kg), and administered XP-10(125, 250 and 500 mg/kg). The organ index and weight were investigated, and the expression of Treg cells (CD4+ Foxp3+ ) in splenic lymphocytes was detected by flow cytometry. Results XP-10 displays mitogen activity and markedly enhanced the proliferation of primary splenocytes induced by ConA and LPS. XP-10 (250 μg/mL) significantly increased the proliferation in anti-CD3-induced splenocytes proliferation. Furthermore, XP-10 increased the secretion of IFN-γ(P<0.05) and IL-6(P<0.05 and P<0.01) in ConA stimulation spleen T lymphocytes. Nevertheless, XP-10 had no influence on IL-2. Finally, administration of XP-10 in immunosuppressive model in mice can antagonise the reduction of organ index, promoted the spleen T cell proliferation. Compared with vehicle group, the proportion of Treg cells (CD4+ Foxp3+ T cells) are decreased(P<0.05). Conclusion The polysaccharide component XP-10 of Artemisia scoparia has good immunomodulatory activity both in vivo and in vitro, and its mechanism may be related to promoting the secretion of cytokines IFN-γ and downregulating the expression of Treg cells. It may have certain application prospects in anti-tumor immunoadjuvant drugs. It proved that XP-10 exerted significantly immunoregulatory activity in vivo and in vitro, the mechanism of action may be related to inhibition the expression of Treg cells and enhance the production of IFN-γ, thus promoting T lymphocytes proliferation and anti-tumor immunological effect. This study will provide basis for the treatment of polysaccharide composition from Aconitum brachypodum in anti-tumor immunological therapy.