HA is a natural biotic component, widely existing in skin and any other tissue. It has outstanding moisture keeping ability, thus called Natural Moisturing Factor (NMF) in the world. It is the best component used in cosmetics for moisture keeping in the nature. When HA applied to the skin, macromolecular HA can form an air permeable thin layer and keep the skin smooth and moist, and protect the skin from bacteria, dust, and ultraviolet ray. With low molecular HA penetrating into corium, it will slightly enlarge blood capillaries, speed circulation of blood, improve inter-mediary metabolism and nourishment absorbing ability of skin, thus eliminating wrinkles, increasing skin's elasticity and delaying its aging. HA as well can further hyperplasia of epidermis cell, clean oxygen free radical, prevent and rehabilitate breach of skin.