Objective To investigate the mechanism of the effect of Bikangyin Mixture on rheumatoid(arthritis) and provide the theoretical basis for clinical practice.Methods To establish the model of(arthritis) induced by adjuvant and observe the regulative effects of Bikangyin Mixture and methotrexate(respectively) on interleukin-1_β(IL-1_β) and tumor necrosis factor-α(TNF-α) through the evaluation of(arthritis) index,X-ray radiological and pathological examination on secondary arthritis and the detection of serum cytokines.Result After the treatment with Bikangyin Mixture and methotrexate the arthritis index changed obviously with a significant difference compared with the model group(P<0.05).The order of pathological change degree from high to low was as follows: the model group,methotrexate group and(Bikangyin) Mixture group.There was a significant difference(P<0.05) in the levels of IL-1_β and TNF-α between the control group and other groups,while there was no significant difference between(Bikangyin) Mixture group and methotrexate group(P>0.05).Conclusion The abnormal increase of IL-1_β and TNF-α was related closely to rheumatoid arthritis.Bikangyin Mixture could decrease the(concentrations) of serum IL-1_β and TNF-α level and control or inhibit the development of rheumatoid(arthritis).