A comprehensive analysis is reported in 376 healthy middle and old-age persons, including measurements of bone mineral content (BMC) of the mid-radias, pituitary sex hormones (RIA), serum calcium, phosphate, albumin, alkaline phosphatase, urinary calcium, phosphate, hydroxyproline (BCA), daily intake of protein and calcium, physical exercise and activity, body weight, amenorrhea etc. Results showed that the preponderance of bone resorption over bone formation is the essential pathophysiological change of involutional osteoporosis. For females, bone loss is regulated mainly by estrogen in presenile group, co-regulated by estrogen and androgen in senile group. For males, urinary hydroxyproline excretion is also regulated by estrogen A remarkable correlation was observed between BMC and the following factors: serum calcium, urinary calcium, hydroxyproline, body weight, physical exercise, amenorrhea, intake of protein and calcium. Our data indicated that the intake of calcium daily in old chinese should not be lower than 700 mg (male) and 900 mg (female), protein should not be lower than 60-70 g. The age of onset, prevalence rate and BMC average reduction rate of osteoporosis in chinese were also observed in the studies.