OBJECTIVE To evaluate the intervention effect of Caulis sinomenii compatible with prepared Aconiti Lateralis on bone destruction in rheumatoid arthritis （RA）model rats ，and to investigate its mechanism. METHODS Totally 40 SD rats were randomly divided into blank group ，model group ，positive control group （indomethacin 0.013 5 g/kg）and C. sinomenii compatible with prepared Aconiti Lateralis group （C. sinomenii 1.08 g/kg+prepared Aconiti Lateralis 1.35 g/kg）according to body mass ，with 10 rats in each group. Except for the blank group ，all the other groups made RA rat models by injecting type Ⅱ bovine collagen. Rats in each group were given corresponding drugs or distilled water intragastrically. The general information ，body weight ，foot swelling and arthritis index （AI）scores of rats in each group were recorded. After the 30th day of administration ，the changes of ankle bone in rats were detected by small animal CT machine. The levels of inflammatory factors [interleukin- 31（IL-31），IL-25 and IL- 3] and chemokines [receptor activator of nuclear factor κB ligand（RANKL），receptor activator of nuclear factor κB （RANK）and osteoprotegerin （OPG）] in serum were detected by enzyme-linked immunosorbent assay. Pathological indexes of rat ankle joint were observed by HE staining. Immunohistochemical method was used to detect the expression of RANKL ，RANK and OPG in synovial tissue of rat ankle joint. RESULTS Compared with blank group ，the mental state of the model group was weak ， the activity decreased significantly ，the hair lost luster ，and the body weight decreased significantly on the 12th to 30th days （P＜ 0.05 or P＜0.01）；the swelling degree of the foot was significantly increased and the AI score was significantly increased on the 12th to 30th days（P＜0.01）；the ankle joint in model group had rough surface ，obvious tissue damage and serious bone erosion ； serum levels of IL- 31，IL-25，IL-3，RANKL and RANK were increased significantly ，while the level of OPG was decreased significantly （P＜0.01）； the expression of RANKL and RANK in synovium of ankle joint increased significantly ， while the expression of OPG decreased significantly （P＜0.01）. Compared with model group ，the above indexes of administration groups were improved to varying degrees ，and most of the differences were statistically significant （P＜0.05 or P＜0.01）. CONCLUSIONS By inhibiting the RANKL/RANK/OPG signaling pathway ，C. sinomenii compatible with prepared Aconiti Lateralis can inhibit the excessive proliferation of osteoclasts and restore the balance of bone metabolism so as to play a role in protecting bone joints and treating RA.