Taiwan produces an average of 190,000 metric tons of discarded oyster shells per year, of which 26,000 metric tons are unappropriated. In the past, about 70% of discarded oyster shells were used in feed, compost and cultivation media, and their added value was not high.The abandoned oyster shell not only occupies space, low economic value and environmental pollution, this project establishes oyster shell modification technology (0.65 M lactic acid, room temperature reaction for 30 min, 76% calcium lactate can be obtained, and oyster shell dissolution rate up to 88% or more), It is also made into organic acid calcium powder, which is simple in process, time-saving and low in cost. In addition to being used as a nutritional supplement in the future, it can also be combined with various processed products as calcium supplements to promote the utilization of oyster shells. Development towards diversification and high value.