Abstract: Atherosclerosis (AS) is one of the leading causes of death in China. Studies have shown that the formation of AS plaque is its pathological basis and autophagy, as one of the key factors affecting atherosclerosis, plays an important role in the formation of AS plaque. Shell is chitosan oligosaccharides (COS) hydrolysis product, with a variety of biological activity, research has shown that shell COS has significant biological properties such as antibacterial, anti-inflammatory, anti-oxidation, anti-tumor, as well as immune adjustment ability. However, the mechanism of the effect on AS still needs to be further explored and in recent years, the role of COS in regulating autophagy in cardiovascular diseases such as diabetic cardiomyopathy, atherosclerosis, coronary heart disease, myocardial hypertrophy and heart failure has been initially verified. This article reviews the research progress in this area, focusing on the mechanism of COS on AS and related autophagy.