Serum amyloid A has a significant effect on the formation of atherosclerosis as an acute reaction, leading to inflammation by stimulating the release of inflammation factors. It is vital for atherosclerosis that serum amyloid A combined with lipoprotein changes the physiological function of high density lipoprotein. Serum amyloid A can affect the function of vascular endothelium and smooth muscle, and also cause thrombosis,which all promote the development of atherosclerosis.