As a new kind of antiplalete medicine,clopidogrel has been widely used in clinical experiences,especially in patients wtih Acute Coronary Syndrome.Many studies confirmed its good effect in Acute Coronary Syndrome.The application of high-loading-dose of Clopidogrel is attracting more and more attention.In this article,we reviewed the efficacy and security of high-loading-dose of Clopidogrel in Acute Coronary Syndrome.