Objective To evaluate the efficacy of Bondronat in the treatment of pain and osteolysis by using the established rat model of bone cancer pain,and explore its mechanisms. Methods A rat model of cancer pain was produced by intra-tibial of Walker-256 breast cancer cells in SD rats.The rats were randomly divided into three groups:sham group,model group,Bondronat treated group.The analgesic effect of Bondronat was evaluated by means of pain threshold.The anti-osteolysis effect of Bondronat was evaluated by means of radiological scores and HE staining in the bone issues.In order to explore the tentative mechanism of Bondronate's anti-osteolysis,the number of osteoclasts was calculated by TRAP dyeing,the content of PGE_2 in blood plasma was tested by RIA,the expression of OPG was examined by IHC.Results Bandronat could notably increase threshold of thermal and pressure pain of rats with bone cancer pain,and remarkably improve osteolysis induecd by tumor,decrease the number of osteoclast,reduce the content of PGE_2 in blood plasma, up-regulated the expression of OPG.Conclusion Bandronate has an obvious analgesic effect and anti-osteolysis function on rat model of bone cancer pain induced by W256 tumor cells.The mechanism could be associated with:reducing PGE_2 in blood plasma,up-regulating the expression of OPG,decreasing the number and activeness of osteoclast.