AIM:To measure the bone mineral density and the relative effective factors of osteoporosis in the different age groups, so as to study the relationship between both, and will offer the theoretical foundation on the prevention and treatment of osteoporosis in the old men.METHODS:Forearm bone mineral density were measured by dual energy X ray absorptiometry (DEXA); By using full automatic biochemical analytic instrument to measure serum calcium (Ca), phosphorus (P); By using radio immunoassay to measure serum parathormone(PTH),Calcitonin(CT),1,25(OH)2 D3,25(OH)D3, interleukin 6(IL 6).Ninety seven old men were divided into osteoporosis group and non osteoporosis group, were compared with normal group of men under sixty years old.RESULTS:Some results such as bone mineral density, CT,1,25(OH)2D3 and 25(OH)D3 showed decrease , while some results such as serum PTH and IL 6 showed increase with aging.The former in osteoporosis group were also significantly lower than those in non osteoporosis group (P< 0.05). The latter in osteoporosis group were also significantly higher than those in non osteoporosis group(P< 0.05-0.001).CONCLUSION:The change of the above relative effective factors lead to the following result.Bone resorption is increasing and bone formation is decreasing.These cause bone loss,at last, osteoporosis comes up. AIM: To measure the bone mineral density and the relative effective factors of osteoporosis in the different age groups, so as to study the relationship between both, and will offer the theoretical foundation on the prevention and treatment of osteoporosis in the old men. METHODS: Forearm bone mineral density were measured by dual energy X ray absorptiometry (DEXA); By using full automatic biochemical analytic instrument to measure serum calcium (Ca), phosphorus (P); By using radio immunoassay to measure serum parathormone (PTH) CT), 1,25 (OH) 2 D3,25 (OH) D3, interleukin 6 (IL6) .Ninety seven old men were divided into osteoporosis group and non osteoporosis group, were compared with normal group of men under sixty years old .RESULTS: Some results such as bone mineral density, CT, 1,25 (OH) 2D3 and 25 (OH) D3 showed decrease, while some results such as serum PTH and IL 6 showed increase with aging. The former in osteoporosis group were also significantly lower than those in non oste The latter in osteoporosis group were also significantly higher than those in non-osteoporosis group (P <0.05-0.001). CONCLUSION: The change of the above relative effective factors lead to the following result. Bone resorption is increasing and bone formation is decreasing.These cause bone loss, at last, osteoporosis comes up.