In addition to visible light, there are also ultraviolet rays in sunlight, and the damage caused by ultraviolet rays to the skin is the most effective and accumulative of all exogenous age-causing factors. Solar UV rays can be divided into long-wave UVA, medium-wave UVB and short-wave UVC according to their wavelengths, and the longer the wavelength, the greater the damage to the skin. Short-wave UVC is usually absorbed by the ozone layer and rarely radiates to the ground. In hot weather, the damage to skin caused by not applying sunscreen is mainly manifested as skin problems caused by long-wave ultraviolet (UVA) and medium-wave ultraviolet (UVB) rays. 1, long-wave ultraviolet (UVA) can lead to skin aging, such as skin wrinkles, roughness, sagging, reduced elasticity, pigmentation, etc.; 2, medium-wave ultraviolet (UVB) can induce or aggravate a variety of light-related skin diseases, such as sunburn dermatitis, polymorphic sun rash, acne, facial dermatitis, and even skin cancer. Therefore, sun protection is especially important. General ways to protect yourself from the sun include applying sunscreen products, using sunscreen clothing, hats, umbrellas, sunglasses and other items, and eating sunscreen foods. In addition, we should avoid exposure to sunlight at the most intense time of the day; sunscreen is best applied 20-30 minutes before going out, the amount should be enough to cover the skin, and it is recommended to reapply every 2 hours or so; regardless of cloudy days, rain or indoors, you should also apply sunscreen as usual; if necessary, you can use medical beauty means of scientific skin care.