Abstract: Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a serine protease that is produced mainly in the liver. As a member of the proprotein convertase family, PCSK9 binds to the LDL receptor (low-density lipoprotein receptor (LDLR) to allow it to enter the lysosome for degradation, thereby inhibiting the recirculation of LDLR to the cell surface for removal of plasma LDL cholesterol (low-density lipoprotein cholesterol, LDL-C). This inhibits the recirculation of LDLR to the cell surface to perform the function of removing low-density lipoprotein cholesterol (LDL-C) from plasma, which leads to hypercholesterolemia. Existing studies have shown that PCSK9 is closely associated with the development of various cardiovascular diseases and has shown the potential as a new therapeutic target in cardiovascular disease research. Here, we summarize the structure and function of PCSK9 as an entry point and review the progress of PCSK9 research in various cardiovascular diseases.