BACKGROUND: Osteoporosis can easily lead to a decline in the self-care ability of middle-aged and elderly people, and an increase in mortality and related medical expenses. The relationship among the main body components of the human body (fat, muscle, and bone) has not been clarified. Therefore, it is necessary to study their relationship and identify potential predictors of osteoporosis in patients. OBJECTIVE: To investigate the correlation between body composition and bone mineral density of the middle-aged and elderly people. METHODS: A total of 109 middle-aged and elderly people were selected as subjects, and their heights, body mass and other information were recorded. The dual-energy X-ray bone densitometer was used to detect the bone mineral density and body composition. According to the results of body mineral density, the subjects were divided into an osteoporosis group and a non-osteoporosis group. The distribution and relationship of basic data, bone mineral density, bone mineral content, lean mass and fat mass of each part were analyzed between the two groups. Chi-square test was used to detect the ratio of osteoporosis in different sexes, and Pearson correlation analysis was used to obtain the correlation degree of each factor and bone mineral density. RESULTS AND CONCLUSION: Women were more likely to suffer from osteoporosis. The age of the osteoporosis group was significantly higher than that of the non-osteoporosis group. Body mass, body mass index, bone mineral density, bone mineral content (overall, head, trunk, lower limbs), lean mass (overall, head, trunk, lower limbs), and fat mass (overall, head, upper limbs, lower limbs) in the osteoporosis group were significantly lower than those in the non-osteoporosis group. Pearson correlation analysis indicated that the bone mineral density of middle-aged and elderly people was significantly positively correlated with height, body mass, bone mineral content (overall, head, trunk, upper limbs, lower limbs), lean mass (overall, head, trunk, lower limbs) and fat mass (head), and negatively correlated with age. Therefore, osteoporosis is more common in women, and the middle-aged and elderly people with osteoporosis are older. Their bone mineral content, lean mass and fat mass of each part are lower than those without osteoporosis. The bone mineral density of the middle-aged and elderly people is highly correlated with the bone mineral content and lean mass of each part. Therefore, body composition can be used as an indirect reference index to evaluate the bone health status. Bone mineral content, lean mass and fat mass of each part have certain influence on the bone mineral density. [ABSTRACT FROM AUTHOR]