Abstract: OBJECTIVE To study the anti-inflammatory effect of tripterine on bovine type Ⅱ collagen-induced arthritis in mice and its mechanism of action on T cells. METHODS DBA/1J mice were used to induce CIA model induced by bovine type Ⅱ collagen. After the model was established， tripterine of 2 mg/kg was given to the mice and the joint score was recorded. The mice were sacrificed after 70 d of secondary immunization. The levels of IL-17， IL-6 and TGF-β in the plasma of mice were detected by ELISA. Pathological changes of the joints were observed by HE staining. Flow cytometry was used to detect the ratio of Th17 to Treg in mouse spleen cells. RESULTS The joint scores of tripterine in mice were significantly lower than that in model group (P<0.05). HE staining showed that tripterine improved the synovitis infiltration (P<0.05)； ELISA showed that tripterine significantly decreased the levels of Th17-associated cytokine IL-6 (P<0.01). Flow cytometry showed that tripterine increased the proportion of Treg cells (P<0.05) while significantly decreased the proportion of Th17 cells in the spleen of mice (P<0.01). CONCLUSION  Tripthenin can effectively alleviate the symptoms of joint inflammation in CIA mice， inhibit synovitis inflammatory cell infiltration， angiogenesis and cartilage destruction. Tripterine treatment of CIA mice inflammation may be through the reduction of IL-6 secretion in CIA mice with anti-inflammatory cytokines involved in the immune balance regulation process.