to evaluate objectively the efficacy and safety of Duyiwei Capsule in treatment of arthritis deformans. Method: Randomized, single-blinded clinical research method with multiply centers and positive control group was used to study 103 cases enrolled from December 2005 to October 2006: the treat group(69 cases, treated with Duyiwei Capsule), and control group (34 cases). After a therapeutic course of eight months, evaluation was based on improvement of main symptoms, signs, and relevant indexes(ESR, CRP,RF). Result: Total effective rates were 81.16% and 76.47% for treat group and control group respectively. The difference was not significant(P>0.05). Both groups could lower levels of ESR, CRP and RF, while treat group did significantly better in alleviating morning stiffness(P<0.05). There were little notable side effects in both groups. Conclusion: Duyiwei Capsule is effective and safe for arthritis deformans.