Hyaluronic acid, also called hyaluronic acid, is a normal substance found inside the human skin tissue and can also be synthesized. When the human skin is in a dry condition, if there is an adequate amount of hyaluronic acid, it can play a role in properly protecting the skin. Generally this substance is widely used in the medical beauty industry. This substance has certain water absorbing properties and has a restorative and water retaining effect on the skin so that the skin does not look too dry. Hyaluronic acid in general can be used in the stratum corneum, gradually forming a water-rich film while transporting water inward and outward. When the environment is dry, it can also rely on the sealant to reduce its evaporation of water to the outside, and can play a moisturizing role, so it is more widely used in clinical practice.