Objective To explore the possible mechanism of Yishen Huoxue Zhitong Decoction（ 益肾活血止痛方）in the treatment of bone metastases. Methods A total of 40 SD rats were randomly divided into Chinese medicine group

zoledronic acid group

model group and sham operation group

with 10 rats in each group. Except the sham operation group

3 μl of rat breast cancer Walker 256 cell suspension was slowly injected into the bone marrow cavity of rat tibia to establish a bone metastasis model in other groups. The drug was administered on the 5 th day after modeling

and the zoledronic acid group was given zoledronic acid solution intraperitoneally on the 5 th

7 th

9 th

12 th

14 th

16 th

and 19 th day

with 30 μg/kg each time; Yishen Huoxue Zhitong Decoction 0. 5 ml（ concentration 1. 92 g/ml） was intragastrically administered. The sham operation group and the model group were given normal saline 0. 5 ml once a day for 3 weeks. The tumor volume of each group was observed. The degree of bone destruction was scored by X-ray film. The pathological morphology of the tibia was observed by HE staining. The osteoprotegerin（ OPG） and nuclear factor κB receptor activating factor（ RANK）

nuclear factor kappa B receptor activating factor ligand（ RANKL） protein and mRNA expressio were detected in the tibia. Results Compared with the model group

the sacral tumor volume and bone destruction were decreased in the Chinese medicine group and the zoledronic acid group

and the expression of OPG protein and mRNA in the tibia was increased

The expression of RANKL

RANK protein and mRNA were decreased（ P < 0. 05）. There was no significant difference between the Chinese medicine group and the zoledronic acid group in all indicators（ P > 0. 05）. Conclusion Yishen Huoxue Zhitong Decoction can inhibit the growth of rat bone metastases

and its mechanism may be related to the activation of OPG expression in tibia and the inhibition of RANKL and RANK activation.