Abstract: Objective To investigate the association between obesity and osteoporosis in men aged above 50 in Chengdu. Methods Male participants aged above 50 were recruited from those who visited West China Hospital of Sichuan University for health examinations. Bone mineral density was measured by MetriScan Bone Densitometry. The participants were divided into three groups according to T values: normal, osteopenia and osteoporosis. Results About 5.75% (525 cases) of the 9 135 male participants had osteoporosis. The three groups had significant different anthropometric parameters, including body mass, waist circumference, hip circumference, body mass index (BMI), waist-hip ratio (WHR), waist-height ratio (WHtR), a body shape index (ABSI), and body roundness index (BRI)( POR) of 0.443 〔95% confidence interval ( CI): 0.342-0.574), 0.580 (95% CI: 0.454-0.740), 0.587 (95% CI: 0.460-0.751), 0.664 (95% CI: 0.516-0.854〕, 1.369 (95% CI: 1.069-1.751), 0.634 (95% CI: 0.497-0.809), and 1.357 (95% CI: 1.047-1.758), respectively, for osteoporosis compared with those with the lowest quartile (Q1). The area under cures (AUC) of receiver operator characteristic (ROC) curve of BMI for osteoporosis was 0.606 (95% CI：0.580-0.632). Conclusion Large body mass was negatively associated with osteoporosis in middle and old aged men. BMI is the strongest predictor of osteoporosis. Further longitudinal studies are required to verify such asscoiations.