Objective To observe the effects of triptolide on the expressions of TNF-α and IL-10, the two cytokines of γδT lymphocytes in the peripheral blood of the rat with collagen-induced arthritis (CIA) in order to investigate the behavior of the γδT lymphocytes in CIA and the immunoregulation of triptolide over the γδT lymphocytes.Methods Wistar rats were used to induce the animal model of CIA by intradermally injecting bovine type II collagen at the back and the root of the tail. After being treated with triptolide, the peripheral blood was taken from the model rat for separating γδT lymphocytes. The flow cytometer and the TNF-α and IL-10 antibodies directly labeled with fluorescence were used to detect the expression of the intracellular cytokines of the γδT lymphocytes at the single-cell level. Results The percentage of γδT lymphocytes, (6.96±0.74)%, in the total lymphocytes; the percentage of the expression of intracellular TNF-α of γδT lymphocytes; (2.22±0.36)%; and the percentage of the expression of intracellular of IL-10, (1.00±0.20)%; were markedly decreased in the peripheral blood of the model rats, as compared with those in the normal control rats (P<0.01). After the treatment with triptolide, all the three above-mentioned criteria were restored to their normal level. Conclusion Triptolide can exert an effect for treating rheumatoid arthritis, of which the mechanism may be its regulating the amount of γδT lymphocytes and the expressions of TNF-α and IL-10.