Objective: To investigate the ethnic differences in osteoporosis (OP) and body composition (BC) and their relationship in the Maonan, Mulam, Hmong, and Yao minorities in China.Design: A total of 860 Maonan, Mulam, Hmong, and Yao women were included in this cross-sectional study. Demographic, health history, and lifestyle information was collected using questionnaires. BC was measured through bioelectrical impedance analysis, and bone mineral density (BMD) was assessed via calcaneal quantitative ultrasound.Results: Compared with premenopausal women, postmenopausal women exhibited a lower fat-free mass (FFM), muscle mass (MM), limb muscle mass, and T-score but a higher waist-to-hip ratio and prevalence of OP in each minority (p<.05). After adjustment for age, Hmong women displayed the highest body mass index, fat mass, percentage of body fat, visceral fat, and subcutaneous fat contents, while Yao women presented the highest T-scores and lowest prevalence of OP among the four minorities (p<.05). Having a greater number of children and an older age were significant risk factors for OP in all ethnic groups (p1). In addition, our results revealed that FFM and MM exhibited exactly the same weak positive relationship with the T-score (r=0.081, p<.05) after adjusting for menopausal status and age in all of the participants. Furthermore, significant ethnic differences in the relationship between BC and the T-score existed in the four minorities studied here.Conclusions: BC and OP prevalence varied by menopausal status and ethnic group, and ethnic-specific relationships between BC and BMD were present in the four minorities. More research is needed to further investigate the ethnic differences in BC, OP, and risk factors for lower BMD to develop targeted prevention strategies to reduce the burden of OP across different ethnic groups in China.