High-fat diet plays an important role in the pathogenesis of AD. This paper reviews the possible pathogenesis of Alzheimer’s disease in recent years，and further expounds the possible mechanism of high fat diet causing Alzheimer’s disease:High fat diet increases the content of saturated free fatty acids in plasma and speeds up the pathological process of AD; High fat diet promotes the occurrence of AD by influencing blood lipid levels;A high-fat diet will lead to the production of large amounts of fat and cause chronic inflammation，the inflammatory factors produced cross the blood-brain barrier and stimulate neuroinflammatory cells;High-fat food will affect the gut bacteria，which in turn affect the microbiota - brain - gut axis，then lead to the AD. Based on the above mechanisms，we can treat or prevent AD by reducing free saturated fatty acids， regulating lipid metabolism disorders，improving inflammation，and regulating intestinal flora.