Elevated low density lipoprotein cholesterol (LDL-C) is a major risk factor for cardiovascular disease. Studies show that proprotein convertase subtilisin/kexin type 9 (PCSK9) is a circulation enzyme and serves a pivotal function in the degradation of low density lipoprotein receptor, which contributes to the decrease in hepatic cholesterol uptake and increase in circulating LDL-C. PCSK9 inhibitor can significantly elevate the surface of low density lipoprotein receptor of liver cells and bond more LDL-C to decrease the level of LDL-C. Thus PCSK9 has emerged as a popular target for the development of new cholesterol lowering drugs and therapeutic intervention of cardiovascular disease. In this article, the history, mechanism of action, metabolic effects of PCSK9 and the clinical outcomes of PCSK9 inhibitors will be briefly reviewed.