Abstract: Objective The explore the preventive effects of Yishen Juanbi Decoction on bone metabolism disorder associated with ankylosing spondylitisby observing the effect of Yishen Juanbi Decoction on proliferation of rat osteoblasts and osteoclasts. Methods Yishen Juanbi decoction was prepared firstly,and the serum containing Yishen Juanbi decoction was prepared following intragastricgavage to rats.The osteoblasts and osteoclastswere isolated and differentiated by stainings of Van kossa,ALP,TRAP and toluidine blue staining.The cells were divided into placebo-treated group,low,medium and large doses of serum containing Yishen Juanbi decoction groups,Diclofenac Sodium control group and Alendronate Sodiumcontrol group.The Cell Counting Kit 8(CCK8) test was conducted to assessthe activities of osteoblast and osteoclast cells.The alkaline phosphatase activityin the cell culture supernatant was tested. Results The serum containing Yishen Juanbi decoction significantly promoted the proliferation and alkaline phosphatase secretion of rat osteoblast in vitro,and increased with the levels of serum.On the other hand,the decoction serum significantly inhibited the proliferation of rat osteoclast in vitro,positively with the contents of serum. Conclusions Yishen Juanbi Decoction can promote the proliferation of osteoblast and improve the activity of osteoblast,andsimultaneously inhibit the proliferation of osteoclast,the effects increased with the doses of decoction.The experiment suggests that Yishen Juanbi Decoction can improve the bone metabolism disorder associated with ankylosing spondylitis.