The aging of the human body is most easily reflected in the skin, and the culprit of skin aging is not natural aging, but more often caused by photoaging. In the daily skin care program, sunscreen can be said to occupy an important position, because the sun does not only lead to tanning, more importantly, will cause skin photoaging. Skin aging can be divided into internal and external two: 1, internal aging: also known as natural aging, determined by individual genetic factors 2, external aging: mainly caused by light aging. Ultraviolet light is the most important factor, so external aging is commonly defined as light aging. In addition, smoking, haze, car exhaust, environmental pollution, etc. will accelerate skin aging. What is photoaging of the skin? After the age of 25, our face gradually starts to show a lot of problems, such as pigmentation abnormalities (age spots, sun freckles, etc.), skin laxity, fine wrinkles, facial redness, enlarged pores, and dull skin color. These changes in our face are not aging in the true sense of the word, which is generally referred to in dermatology as photoaging. It means that light induces premature aging changes in the skin. The external aging of the skin is photoaging, which is mainly caused by ultraviolet radiation. It is manifested by skin roughness, thickening, laxity, deep and coarse wrinkles, localized excessive pigmentation or capillary dilatation, and may even appear various benign or malignant tumors. Factors leading to skin photoaging: 1, exogenous factors: mainly UVA and UVB involved in the pathogenic process of photoaging, UVB irradiation can cause skin erythema and delayed pigmentation, damage to the skin’s moisturizing ability, so that the skin becomes rough, wrinkled, long-term UVB irradiation can make the skin thickening of keratin. UVA is the main culprit in the skin tanning, and its photochemical effect and photobiological effects are not as pronounced as that of UVB, but the sunlight UVA is more than UVB, but it is more than UVB. UVA in sunlight than the UVB dose many times higher, and penetration ability, penetrate the deep layers of the skin, so in the cause of skin photoaging UVA also has an important impact. 2, endogenous physiological factors: from receiving sunlight exposure, skin photoaging pathogenic effects have begun to accumulate, so it is emphasized that from infancy should pay attention to the protection of sunlight damage. In addition, with the growth of age, the skin structure also occurs corresponding changes, such as epidermal stratum corneum integrity, hydration and lipidation, epidermal thickness, color and skin in the light-absorbing material content changes, etc., these factors can affect the ultraviolet radiation in the sun reflection, scattering, absorption and penetration of the situation, which affects the development of skin photoaging. Skin color also has an impact on skin photoaging, skin color is mainly determined by the melanosomes in the epidermis, and melanosomes of various wavelengths of ultraviolet and even visible light and infrared light are well absorbed, so the epidermis in the melanosomes is the defense of dermal tissue from ultraviolet radiation damage to the natural barrier. 3.Pathological factors: a variety of skin diseases can make the body’s sensitivity to ultraviolet radiation increased, and appear to light damage-based clinical manifestations. 4, other: the above two aspects of the skin is the main reason for the problem of photo-aging, in addition to occupational, geographic latitude and altitude, etc. can also cause each person’s skin photo-aging. Solutions for skin photoaging: At present, laser/light-based non-surgical methods are increasingly becoming the first choice of treatment for many candidates and doctors to improve skin aging problems. 1, peeling laser treatment: peeling laser mainly includes the wavelength of 10600nm carbon dioxide (CO2) laser and wavelength of 2940nm erbium yttrium aluminum garnet (Er: YAG)) laser. Although the efficacy of total resurfacing lasers is very significant, however, large areas of peeling are prone to the formation of persistent erythema, skin sensitivity, scarring, especially hyperpigmentation, so it is difficult to be widely carried out in the Asian population. 2, non-exfoliative laser / light treatment: non-exfoliative laser / light mainly includes pulsed intense light (500-1200nm), Nd: YAG laser (Q-switch 1064nm, long pulse width 1064nm, 1320nm), semiconductor laser (1450nm), erbium: glass laser (1540nm), pulsed dye laser (585nm, 595nm), KTP laser (wavelength 532nm), radio frequency, infrared technology, focused ultrasound and so on. The principle of action is selective photothermal effect: after the laser/photon acts on different target chromophores (melanosomes, hemoglobin, water), heat is generated, which stimulates the function of fibroblasts and synthesizes more collagen, elastin and hyaluronic acid, thus achieving the effect of wrinkle removal and skin tightening. 3, fractional laser: fractional laser can be divided into peeling fractional laser and non-peeling fractional laser. ①Exfoliative fractional laser: CO2 fractional laser, Er pixel laser, Er:YAG super platform, radio frequency fractional, ion beam laser, radio frequency microneedle, etc.; its characteristics: the epidermis and the superficial dermis at the same time be vaporized and coagulated, the formation of postoperative fractional scabs, 3-7 days peeling. ②Non-exfoliative fractional lasers are mainly: 1060nm, 1320nm, 1450nm, 1550nm lasers. Due to deviation from the absorption peak of water molecules, the laser will not produce vaporization and stripping phenomenon after acting on the tissue. The energy penetrates into the dermis and stimulates skin renewal through photothermal action. Fractional laser retains the high performance of traditional peeling laser, but also reduces the side effects, and the recovery period after the operation is greatly shortened, or even no recovery period at all, which is another milestone progress in photoaging treatment.