After enzymatic hydrolysis, collagen forms hydrolyzed collagen. Its molecular structure and molecular weight change, which changes its water absorption, solubility, water retention and other functional properties. Hydrolyzed collagen with larger molecular weight has stronger relative hydrophobicity and can better maintain the molecular configuration, so it has better oil absorption, emulsification and emulsification stability in a two-phase system. Therefore, it is used in oil-based cosmetics. It is required to add hydrolyzed collagen with a lower degree of hydrolysis and a larger molecular weight; but moisturizing cosmetics require the addition of hydrolyzed collagen with a higher degree of hydrolysis and a small molecular weight, whose polar groups can form hydrogen bonds, ionic bonds and other polar effects It has good water absorption, solubility and water retention. The molecular weight of hydrolyzed collagen is 2000 Dalton and 5000 Dalton, which are suitable for oily cosmetics and moisturizing cosmetics respectively. The chemotaxis of hydrolyzed collagen to fibroblasts stimulates the growth of fibroblasts in the skin, and significantly increases the density of fibroblasts, the diameter and density of collagen fibers, and the percentage of decorin and dermatan sulfate to increase the mechanical strength of the skin. Increased, improved mechanical properties, increased softness and elasticity, stronger moisturizing ability, and improved skin fine wrinkles and deep wrinkles.