Egg yolk lecithin is a kind of phospholipids composed of glycerol, choline, phosphoric acid, saturated and unsaturated fatty acids. It is the basic component of biological membranes such as cell membrane, nuclear membrane and plastid membrane; It has such physiological activities as scavenging free radicals, delaying aging, improving lipid metabolism, preventing atherosclerosis, participating in the formation of cell membrane, enhancing immune function, promoting nerve conduction, improving brain vitality, anti-tumor and promoting the absorption of vitamins A, D and e. it is widely used in food, medicine, cosmetics and other industries.