It is increasingly recognized that calcium supplementation can prevent and treat osteoporosis. However, when many people think about the relationship between calcium supplementation and kidney stones, they take for granted that a high calcium diet will lead to high calcium levels in the urine and increase the risk of calcium oxalate stones, and that calcium supplementation using calcium supplements rather than dietary calcium supplements will cause a higher risk. In fact, this view has been disproved by numerous studies by Chinese and foreign scholars. The vast majority of kidney stones (70% to 80%) are composed of calcium oxalate, and the ratio of oxalate to calcium concentration in the urine is very important for stone formation. The concentration ratio of calcium to oxalate in normal urine is 5:1, whereas the concentration ratio of urine in which calcium oxalate crystals are formed is 1:1, which means that an increase in urinary oxalate concentration has a 15-fold greater effect on the formation of calcium oxalate stones than an increase in urinary calcium. Studies have confirmed that urinary oxalate is more important than urinary calcium in causing kidney stones, and that calcium supplementation can prevent calcium oxalate kidney stones by reducing urinary oxalate concentrations and increasing the urinary calcium/urinary oxalate ratio. In 2006 Jackson et al. reported 449 kidney stones in 18,176 cases in the calcium supplementation group, an incidence of 2.47%, which is much lower than the 12% rate of possible kidney stones in Americans. This study applied extensive statistical data to confirm that calcium supplementation may reduce the incidence of kidney stones, but that excessive calcium supplementation (intake above 2000 mg/d) may increase the risk of kidney stones. Furthermore, according to foreign literature, excessive restriction of calcium intake stimulates vitamin D synthesis in the body, promotes bone decalcification, and increases urinary calcium excretion, thereby increasing the risk of calcium-containing stone formation, which also illustrates the need for calcium supplementation in the prevention of kidney stone formation. Studies have confirmed that dietary calcium intake is negatively correlated with the risk of kidney stones. Currently, the appropriate calcium intake recommended by the Chinese Nutrition Society is 800-1000 mg/day, with an additional 600 mg/day for pregnant women and a tolerable maximum calcium intake of 2000 mg/day. The intake of fruits and vegetables rich in oxalic acid and prone to kidney stones (such as spinach, cocoa, strawberries, tea, etc.) in the daily diet can increase the possibility of kidney stone formation. Calcium supplementation during or immediately after eating can cause some calcium to combine with dietary oxalic acid to form insoluble calcium oxalate, which is excreted in the feces, thus reducing the incidence of hyperoxaluria and kidney stones. Therefore, calcium supplementation at the right time and in the right amount is not only effective in preventing osteoporosis, but also beneficial in preventing kidney stones and reducing the recurrence rate of stones.