The concept of fractional laser was introduced to the market in 2004 by laser medicine experts from Harvard University in the United States, in order to get visible cosmetic results and the lowest risk cosmetic technology. It quickly gained the approval of experts around the world and was quickly applied in clinical treatments. Unlike traditional ablative lasers, fractional lasers treat only a portion of the skin, leaving up to approximately 95% of the skin untouched and the undamaged surrounding tissue wrapped around the damaged tissue allowing for rapid epidermal repair. Like traditional cosmetic lasers, fractional lasers are divided into two categories: non-ablative fractional lasers and ablative fractional lasers, and CO2 fractional lasers are ablative fractional lasers. Its mechanism of action is the fractional photothermolysis theory, in which the fractional laser produces an array of tiny beams arranged to act on the skin, and the skin tissue absorbs the laser energy, forming multiple column-shaped micro thermal damage zones, called microscopic treatment zones or microthermal zones. The MTZ has a diameter of 50-150 μm and a depth of 400-1000 μm. Unlike the conventional laser, which produces lamellar thermal damage, the fractional laser forms a ring-shaped tissue coagulation zone or thermal damage zone around each MTZ. Unlike conventional lasers that produce sheet-like thermal damage, the fractional laser forms a circular tissue coagulation zone or thermal damage zone around each MTZ, with undamaged normal tissues at the periphery, thus enabling rapid skin recovery after treatment. During the recovery process, circular tightening and collagen remodeling of the thermal damage zone around the MTZ produces a multicenter microcontraction, resulting in significant immediate and long-term skin tightening. This combines the advantages of both invasive treatment with rapid and dramatic results, and non-invasive treatment with minimal side effects and short recovery time. Indications: Fractional laser not only rejuvenates the face, but can be used for the treatment of various facial skin disorders. These include: ① improving wrinkles on the face and neck, achieving taut skin, refining pores and improving rough skin texture; ② removing pigmented lesions, including freckles, sun spots, age spots, hyperpigmentation, chloasma and other pigment abnormal lesions. Among them, refractory melasma previously treated by various methods is not only ineffective, but often also causes certain negative reactions, while fractional laser is the only feasible treatment method approved by FDA, but the literature reports varying efficacy, not 100% effective, and its long-term efficacy remains to be observed; ③ remove or reduce acne scars and various trauma scars; ④ treat rosacea, capillary hyperplasia and other vascular diseases; ⑤ apply to various types of skin, including Fitzpatrick type skin; ⑥In addition to treating the face, it can also be used for the treatment of skin diseases in other areas such as the neck, chest, and hands. Fractional laser has the advantages of less trauma, faster healing and fewer complications. Fractional laser peels off the epidermis in a fractional fashion and may have short-term complications such as erythema, edema, and hyperpigmentation; permanent complications rarely occur.