Despite significant advances in medical technology, there is still a lack of methods that can significantly slow down skin aging. Microinvasive facial rejuvenation techniques can be used clinically to help disguise skin aging and improve facial appearance. When used in conjunction with surgical procedures, better results can often be achieved. Skin peeling techniques, commonly known as resurfacing or rejuvenation, are used for erythema associated with photodamaged skin or to improve facial wrinkles and skin pigmentation changes where surgery has failed. There are a number of peeling techniques that can be used, which selectively destroy the epidermis and part of the dermis, and then achieve therapeutic goals through healing recovery of the skin damage [1]. The choice of the type of peel should be based on a number of factors, including the skin type, the defect being treated, and possible complications. At present, the following types of skin peeling techniques and drugs are commonly used in clinical practice. 1, drug corrosive chemical peeling Chemical peeling is the application of one or more corrosive chemicals to produce controlled damage to the epidermis and part of the dermis, and make it re-epithelialization of a technology [2]. Depending on the depth of the controlled injury, chemical peels can be categorized as superficial, moderate, and deep peels. Superficial peels reach only the epidermal layer in depth and are used to improve skin texture and reduce wrinkles. Medium peels cause damage up to the papillary layer of the dermis and are used to treat small wrinkles and hyperpigmentation. Deep peels treat deep wrinkles primarily by affecting the reticular layer of the dermis. The depth of the peel depends on the agent used in the peeling process. The key to chemical peels is to determine the condition of the skin and then select the appropriate agent and peel depth. There are many types of agents used for superficial peels, with alpha hydroxyacetic acid (AHA) or hydroxyacetic acid, low concentrations of trichloroacetic acid, and Jessner’s solution often used. Unlike phenol solution, which acts in an “all or nothing” manner, the penetration of TCA is related to its concentration and time of action, and the depth is easy to control, so it is safer than phenol solution, and is the most commonly used stripping agent at present. Skin preparation should be started 2~3 weeks before the formal application of superficial peeling agents. Tretinoin, hydroxyacetic acid and retinoic acid are usually applied twice daily in combination with other skin care products. The purpose of skin pretreatment is to stimulate the epidermal layer to become structurally dense and homogeneous in texture to improve the effectiveness of the peel application. It is often necessary to perform several skin exfoliations before the results become apparent. Sometimes patient dissatisfaction arises from less than realistic expectations of the outcome. Patient dissatisfaction rate of superficial peeling is relatively high, a survey by Dinner et al. found that among patients who received superficial peeling, the satisfaction rate was 50% for men and 75% for women. 2, retinoic acid (retinoic acid) drugs After noting that acne patients applying retinoic acid skin became smooth, people began to study the use of retinoic acid to treat photodamaged skin. Retinoic acid is a keratolytic drug that has been shown to reverse photodamage to the skin to some extent. Due to its simplicity and ease of use, retinoic acid has become the most commonly used medication for treating photodamaged skin. After application of retinoids, the skin forms new collagen and blood vessels. These new blood vessels help improve skin color and nutrient supply. Clinically, retinoids can smooth the texture of the skin by eliminating very small wrinkles. Retinoids have also been used to treat deeper wrinkles and discoloration. It takes at least 24 weeks of daily application of retinoid creams or gels to show improvement. The advantage of retinoids is their simplicity and ease of use, but some patients (especially men) are reluctant to use the medication for a long period of time and find it difficult to adhere to the daily application of the cream. For such patients, the doctor must fully explain the necessity of adhering to the application of retinoids before starting the treatment. 90% of patients applying retinoic acid cream treatment in the first few weeks of treatment side effects, the occurrence of dermatitis, with flaky erythema, localized swelling, dryness and mild ichthyosis as the main changes. Later gradually disappear. 3, vitamin C It has been observed that ultraviolet radiation can lead to oxidative damage to the skin and affect the skin’s defense system, and has been confirmed that antioxidants have a role in the treatment of photodamaged skin. Vitamin C can reduce the signs of skin aging, presumably because of the ability to scavenge photodamaged skin in the release of free radicals. Vitamin C has also been found to have an important role in collagen formation and to increase collagen synthesis in in vitro experiments. Other antioxidant vitamins (E and K), reactive oxygen species dismutase (SOD), etc. have also been studied. Have also been studied, the results show that they may be effective, but there is a lack of scientific comparative studies. 4, alpha hydroxy acid (AHA) class of drugs Alpha hydroxy acid, also known as fruit acids, is a relatively new drug for the treatment of facial aging. In the United States, alpha hydroxy acid drugs have been sold more than 300 million dollars a year. Alpha hydroxy acids have become a very popular cosmetic treatment due to their ease of application and few complications. Alpha hydroxy acids belong to the group of naturally occurring organic acids, the most commonly used being glycolic acid, lactic acid and hydroxyacetic acid. Other alpha hydroxy acids include malic acid, citric acid and tartaric acid. Hydroxyacetic acid is the smallest molecular weight of the various alpha hydroxy acids, a two-carbon molecule that is colorless, odorless, water-soluble, and non-toxic even when taken inadvertently. Current theories suggest that alpha hydroxy acids act by exfoliating the epidermis and promoting normal epidermal differentiation. Clinically, alpha hydroxy acid improves skin elasticity and smoothes the skin accordingly. At low concentrations, alpha hydroxy acids accelerate epidermal exfoliation by interfering with intercellular ionic binding and reducing keratinocyte junctions. At high concentrations, it can have a keratolytic effect, leading to superficial exfoliation. The strength of the acid determines the depth of tissue penetration. Alpha hydroxy acids are widely used to eliminate fine wrinkles, increase skin thickness, and reduce capillary dilation. After application, histologic observations reveal extracellular matrix rearrangement and thickening of the epidermis and dermis. The majority of patients treated with a low concentration of alpha hydroxyacetic acid cream twice daily for 2 weeks show significant results. alpha hydroxyacid products are available in a variety of dosage forms, including gels, lotions, and creams. Commercial alpha hydroxy acid-based cosmetic care products vary in formulation, but are less acidic than medical preparations. Typical commercially available products have alpha hydroxyacetic acid concentrations ranging from 2% to 20%. Chemical peeling requires a high concentration of alpha hydroxyacetic acid, which when penetrated deeply can cause total dissolution of the epidermis and have an effect on the dermis, inducing the formation of new collagen. The procedure is minimally painful and can be done in a general practice, sometimes multiple treatments may be required for satisfactory results. Complications of alpha hydroxy acid treatment include erythema, crusting, burning and severe oozing. The chance of complications increases with higher concentrations of acid. Scarring or pigmentation changes may also occur with deeper peeling. Photodamage is evident in most patients who engage in a high level of outdoor activity with minimal shading. alpha hydroxy acids are important agents in the treatment of photodamage. Alpha hydroxy acids are attractive to patients because of their efficacy and ease of application, but like retinoids, some patients may have difficulty with long-term daily application. Skin resurfacing (dermabrasion) Skin resurfacing is the continuous removal of the epidermis and part of the dermis by friction. The degree of skin improvement is related to the depth of skin rubbing. Superficial skin abrasion is used to remove exogenous lesions, pigmentation abnormalities, and to reshape scarring. Deeper skin abrasion is used to remove wrinkles and scarring. In addition, some studies suggest that the use of skin rubbing may have a preventive effect on photochemical skin damage and skin tumors. With the widespread use of laser treatments, the use of dermabrasion has declined, but it is still an important technique for re-epithelialization of the skin. Skin rubbing can be accomplished on an outpatient basis with local anesthesia or cryojet anesthesia. The depth of friction should not exceed the middle of the reticular dermis or scarring may occur. Re-epithelialization of the friction wound occurs within 5 to 8 days after the procedure. The new epithelium is very red in color and often requires makeup for coverage. As with laser treatment, sunlight must be strictly avoided during the postoperative recovery period or pigmentary changes may occur. There is a new type of microcrystalline skin friction machine that uses crystal particles that pass over the surface of the skin under pressurized and vacuum suction conditions to achieve friction. This technique is more advanced and has been reported to be very successful, but studies have yet to evaluate its long-term effects. Complications of dermabrasion include long-lasting erythema, hyperplastic scarring, depigmentation and infection. Some patients may not be comfortable with skin rubbing due to the long recovery time and the fact that the skin is different from normal during recovery. The physician must be careful in selecting patients for skin rubbing. As with other procedures, a pre-operative briefing on the expected results of the procedure can help increase patient satisfaction with the procedure. Laser Skin Resurfacing Laser technology is a relatively new technique for re-epithelializing the skin, and its effectiveness depends on the type of laser and the configuration of the laser. Its main advantage is precision, with each laser beam delivering energy that can be quantitatively controlled. This increases the reliability of the technique and facilitates repetition. Lasers are effective in eliminating wrinkles, scarring and pigmentation abnormalities. Hair removal can also be achieved with repeated use of the laser. Early use of continuous wavelength CO2 lasers had limited reepithelialization of the skin because of the high conduction of heat to non-targeted areas, which led to scarring and pigment loss. In recent years improved CO2 laser technology has reduced the damage to non-target tissues by using techniques such as high energy, short pulse or scanning laser delivery systems, thus reducing the incidence of complications. Laser technology is now routinely used for re-epithelialization of the skin and is known as a skin rejuvenation technique. The most obvious shortcoming is persistent post-procedure erythema, which may last 2 to 4 months. The Erbium: Yttrium-Aluminum-Neodymium (YAG) laser system promises to address the shortcomings of CO2 laser technology. The shorter wavelength of the erbium laser reduces tissue penetration and damage to surrounding tissue, and studies have shown that it can reduce postoperative skin erythema. Erbium lasers are often less damaging than CO2 lasers due to limited thermal damage to the tissue and reduced collagen contraction. The depth of laser treatment depends on the energy and number of laser beams. Pretreatment of the skin with retinoic acid accelerates the healing process and should be applied beforehand in most patients. Each laser beam burns a portion of the skin, which can be easily removed. The degree of wound reaction correlates with the depth of the laser burn. When the papillary layer and the superficial reticular dermis are irradiated, basal cell regeneration and dermal collagen formation are enhanced and wound healing is accelerated. Thicker skin or wrinkled areas require multiple irradiations. Laser aftercare is similar to skin rubbing. Complications of laser treatment include persistent erythema, edema, milia formation, burning and itching sensations, transient hyperpigmentation and irregular delayed pigment loss have also been reported and may be more frequent in people of color than in Caucasians. The most serious complications are proliferative scarring and lid ectropion formation. The main advantages of skin reepithelialization with lasers are the flexibility, the short treatment time, and the possibility of treating the lesion in steps. Many doctors abroad are now using lasers in combination with wrinkle removal, brow lifting or other techniques with excellent results. Due to the precision of the energy emitted by the laser, doctors are able to accurately control the degree of re-epithelialization. As a newer skin rejuvenation technique, lasers with mild and superficial effects can reduce postoperative complications, decrease recurrence rates, and provide a gradual step-by-step approach to re-skinning [9]. In addition, the application of lasers to remove hair growth in certain areas is convenient, although recurrence is still possible. Others The use of cryo-spray, high-frequency electrocautery cauterization, and herbal blistering agents can also provide skin exfoliation, which has been reported in China, except that the scope of treatment is limited and the effectiveness of the treatment is closely related to the operator’s manipulative skills. The disadvantages of freezing, electrocautery, traditional Chinese medicine and laser technology are similar to those of skin peeling, and for nationals, some patients may often have skin erythema or pigmentation changes that do not fade away, and it is difficult to cover them up with make-up for a long period of time, which is the biggest trouble. Erbium laser has the potential to eventually solve these problems, but further research is still needed.