Hyaluronic acid (HA) is a straight chain macromolecular mucopolysaccharide composed of repeat disaccharide units of glucuronic acid and N-acetylglucosamine. It widely consists in the extracellular space of human and animal tissue, vitreum, umbilical cord, skin joints synovia and cockscomb, etc. The commercial HA is commonly a sodium salt, called sodium hyaluronate, habitually called hyaluronic acid. HA is a new biological at home and abroad. Its molecular weight is from several ten thousand to several million. Its aqueous solution has outstanding moisture keeping ability, high viscoelasticity and lubricity. It is widely used in cosmetics, pharmacy and health and beauty food.