The human skin is in direct contact with the external environment in which it is located and is the largest organ of the human body, which maintains the stability of the internal environment of the body. The skin is divided into three layers, namely the epidermis, dermis and subcutaneous tissue: I. Epidermis: 1, stratum corneum: the outermost part of the epidermis tissue, is the protective layer of the skin, when the stratum corneum thinning skin prone to sensitivity, allergies, red blood pigmentation, etc., to protect the health of the stratum corneum is best cleaned with mild cleaning products to avoid excessive cleaning damage to the skin; 2, transparent layer: common in the hands and feet skin Thicker parts of the skin, can play a protective, buffer, reduce friction; 3, the granular layer: the role of waterproof, ultraviolet light also has a certain resistance function; 4, the spiny cell layer: the main connection between the basal layer and the epidermis, can save water, absorb nutrients, maintain skin elasticity; 5, the basal layer: the bottom layer of the epidermis, the existence of proliferation, differentiation potential of epidermal stem cells, can play a regenerative repair It can play the role of regeneration and repair. Second, the dermis: contains collagen fibers, elastic fibers, repair, collagen and other functions, damaged more difficult to repair, but also the more important skin tissue in daily skin care. Third, the subcutaneous tissue: contains blood vessels, lymphatic vessels, nerves, sweat glands, hair follicles, etc., can cushion the pressure, have stored energy, insulation and other functions. With the protection of the skin in the outer layer, it can regulate the body’s temperature in time to avoid damage from external harmful factors. At the same time, the skin can also absorb water and nutrients through the stratum corneum and hair follicles, and secrete and excrete through sebaceous glands and sweat glands, thus completing skin metabolism. Therefore, the skin has a very good protection function for the human body, such as the occurrence of skin diseases, should be timely medical treatment, so as not to affect the health of the body.