A method of preparing amorphous calcium phosphate (ACP) for oral care and its compositions are disclosed, and the method of preparing amorphous calcium phosphate comprises following steps: (a) cleaning and pulverizing an oyster shell； (b) sintering the oyster shell to obtain a calcium powder； (c) dissolving the calcium powder in water to obtain a calcium solution； and (d) adding the calcium solution into a phosphate solution to obtain amorphous calcium phosphate. The method of preparing amorphous calcium phosphate of the present invention not only can simplify the process and reduce the cost, but also can solve the problem of environment pollution resulting from the waste of the oyster shells. In addition, the amorphous calcium phosphate prepared by the method of the present invention further comprises some trace elements, such as F and Sr, which can be used in oral care to improve the dental health.本發明係有關於一種口腔保健用之非晶性磷酸鈣之製備方法及其組成物，其中非晶性磷酸鈣之製備方法，包括下列步驟：(a)清洗並粉碎一牡蠣殼；(b)燒結牡蠣殼，以製得一含鈣粉末；(c)將含鈣粉末溶於水中，製得一含鈣溶液；以及(d)滴加含鈣溶液於一磷酸鹽水溶液中，以析出一含氟與鍶微量元素之非晶性磷酸鈣。本發明非晶性磷酸鈣之製備方法，除了製程簡單、成本低廉及解決牡蠣殼廢棄物污染的問題外，其組成物不僅具有口腔保健等功效，更含有氟、鍶特殊之微量元素，增強牙齒健康之功能。
