Beauty lovers know that moisturizing, sunscreen is the key to the whole skin care, especially now that it is summer, sunscreen when it becomes a good choice for skin care, so it is important to choose a good sunscreen. 1, sunscreen agent classification: 1) chemical ultraviolet absorber, can selectively absorb light in the long-wave, medium-wave ultraviolet light, and then released in the form of other visible light to play a role in sunscreen, common aminobenzoic acid and its esters, salicylic acid esters, cinnamic acid esters, benzophenone and its derivatives, methane derivatives, etc., chemical sunscreens can be absorbed, and therefore there may be irritation reaction, causing Skin sensitivity, but in fact, the use of more physical sunscreens refreshing, colorless. 2) Physical sunscreens: mainly through the reflection or scattering effect to reduce the contact between ultraviolet radiation and the skin to play a role in sunscreen, common titanium dioxide, zinc oxide, talcum powder, etc., but with a feeling of heavy, feel not very ideal. 3) biological sunscreen: can be cleared to reduce oxygen free radicals to slow down tissue damage, promote skin repair after sun exposure to achieve the effect of sunscreen, common vitamin C, E, SOD, coenzyme Q and aloe vera, scutellaria and other traditional Chinese medicine extracts. Most of the sunscreens on the market today are mixed sunscreens, which can be seen on the ingredient labeling of cosmetic packaging. 2, sunscreen product labeling: the main 1) SPF (Sun protection factor) refers to sunscreen products on the protection value of medium-wave ultraviolet radiation, is now widely used in the international community. 2) PA, refers to sunscreen products on the protection value of long-wave ultraviolet radiation to the “+” logo, PA + means light shade, PA ++ means medium shade, PA ++ means medium shade, PA ++ means medium shade, PA ++ means medium shade, PA ++ means medium shade, PA ++ means medium shade, PA ++ means medium shade, PA ++ means medium shade, PA ++ means medium shade, PA ++ means medium shade. PA++ means moderate blocking and PA+++ means high blocking. Long-wave ultraviolet rays can lead to the destruction of dermal collagen fibers, causing skin aging, wrinkles, so the choice of sunscreen products must look at the PA value. 3, how to choose sunscreen: usually so: general skin type SPF8 ~ 12, PA + + +; light-sensitive people SPF15 ~ 20, PA + + + +; office workers SPF10 ~ 15, PA + + +; the countryside, seaside SPF30, PA + + +. If swimming, you can choose waterproof sunscreen. Fair skin, sunscreen index should be high. Indoor work can be reapplied every 4~5 hours sunscreen products; outdoor work should be 2~3 hours to wipe once, waterfront work should be 1~2 hours to reapply.