Abstract: Objective To examine the influence of phytoestrogen-soybean isoflavone on rat's biochemical markers of bone turnover.Methods Wistar rats were given different doses of isoflavone for three months after grouped at random.Serum alkaline phosphatase(ALP),tartrate-resistant acid phosphatase(TRACP),osteocalcin(OC)and 17-β-estradiol(E₂) were determined by kits.Results Soybean isoflavone as a weak photoestrogen didn't have any adverse effects on uterine and ovary.Compared with the control,isoflavone could affect biochemical marker of bone turnover.Isoflavone,at the dose of 41.6mg/kg·bw,suppressed the activity of osteoblastic and osteoclastic and decrease bone turnover of rats.However,ithad more effects on bone resorption than bone formation.Conclusion Isoflavone can adjust the activity of rat's bone metabolic biochemical markers;and prevent the happen of bone loss.