Objective The present study aimed to establish a bone mineral density (BMD) reference database in China and to investigate the prevalence of osteoporosis in Chinese adults aged 50 years and older using dual energy X-ray absorptiometry (DXA). Method A total of 75321 examineers over 25 years old who underwent health checkups in 7 health check centers between 2008 and 2018 were included. All centers used a GE Lunar-DXA system to measure BMD of the lumbar spine (L1-L4), femoral neck, and total femur. The same European Spine Phantom (ESP) was used for scanning 10 times at every center, a regression equation was generated, and BMD data were cross-calibrated in each center. Peak BMD and standard deviation (SD) were identified according to 5-year age groups, and T scores were calculated based on the peak BMD and SD. Osteoporosis was defined according to the World Health Organization criteria. The prevalence of osteoporosis was standardized based on 2010 national census data for the Chinese population. Result The mean BMD values decreased with age, were highest in North China, followed by Northeast China, East China, and Southwest China, respectively, and increased with body mass index. Males aged 20-30 years and females aged 35-40 years had peak BMD values. Peak BMD values of the lumbar spine, femoral neck, and total femur were 1.09 g/cm2, 0.97 g/cm2, and 0.97 g/cm2 in males, and 1.11 g/cm2, 0.84 g/cm2, and 0.88 g/cm2 in females, respectively. Among all scanned sites, the prevalence of osteoporosis was highest in the femoral neck in males (4.58％) and in the lumbar spine in females (23.38％). The age-standardized prevalence of osteoporosis at any site was 6.46％ in males and 29.13％ in females aged 50 years and older. Based on the 2010 national census data, 10879115 males and 49286542 females currently have osteoporosis. Conclusion Mean BMD values varied according to geographic region, body mass index, age group, and sex in Chinese adults. The age-standardized prevalence of osteoporosis was 6.46％ in males and 29.13％ in females aged 50 years and older.