Facial acne, commonly known as acne vulgaris, is a chronic inflammatory disease of the sebaceous units of the hair follicles. It is a chronic inflammatory disease of the sebaceous units of the hair follicles. According to some scholars, about 80% of teenage men and women suffer from this disease to varying degrees, and more than 20% of adults have persistent acne. Of these, about 52.6% of yellow people will have scarring and/or hyperpigmentation (acne marks) as a sequel. Therefore, in general, severe facial acne is often accompanied by depressed scarring after healing. These severe facial depressed acne scars can have a negative impact on the patient’s social activities and mental health. In addition, there are other causes of similar depressed scarring, such as severe chicken pox, scratches, burns, scalds, electrical burns, falls, knife wounds, car accidents, and even surgery, traditional laser surgery, liquid nitrogen freezing, and various other factors. Traditional treatments for these depressed scars include chemical peels, mechanical skin abrasion, CO2 laser abrasion and surgical treatment. However, chemical peels are mild and tend to cause incurable hyperpigmentation; mechanical abrasion such as skin grinding wheel is not easy to control the treatment depth and does not facilitate precise grinding of single or small depressed scars to achieve the best results; CO2 laser grinding treatment is effective but requires a long recovery period and may cause hyperplastic scarring; surgical treatment can only target single or small depressed scars. Surgical treatment can only be used for single or small depressed scars, and is rarely accepted by patients. Fractional laser technology is a very popular aesthetic technology in recent years and has been widely used to treat depressed scars, enlarged pores, acne marks and improve skin texture. The principle of action is the fractional photothermal action theory, which forms a fractional burn area in the lesion area consisting of many hair-like micro-pulse laser action points arranged in a matrix with intervals to reduce the laser trauma area. These action points have enough energy to penetrate the epidermis of the skin to reach the dermis, stimulate the collagen growth in the dermis, promote collagen reorganization, and then promote the “regeneration” of the skin tissue and a series of skin reactions, while the interval between each laser action point ensures that only a small portion of the skin The interval between each laser action point ensures that only a small portion of the skin is exposed to the laser, and the skin that is not exposed to the laser can be used as a thermal buffer zone, which greatly reduces the thermal damage to the skin and facilitates rapid skin recovery, resulting in significant improvement in skin depressions, skin texture and tone, and enlarged pores in a short period of time and achieving the best clinical results. The fractional lasers currently used in clinical practice include lasers with wavelengths of 1320nm, 1550nm, 1540nm, 1440nm, 2940nm and 10600nm, with increasing penetration depths, and the clinical doctor will select a certain type of fractional laser based on the degree of depression of the patient’s depressed scar, the size and shape of the scar, the patient’s skin texture and the combination of the patient’s subjective requirements. fractional laser for treatment. For complex depressed scars with a variety of manifestations, the physician will select multiple treatments at the same time or apply different fractional lasers at different stages of treatment, which helps to improve the treatment effect, shorten the treatment course, and greatly reduce the occurrence of adverse reactions.