The beauty principle of “microneedling”: “microneedling” can not only improve the accuracy and efficiency of drug delivery, but also has the characteristics of painless and microscopic, “microneedling” is not only in the field of biomedicine has been widely used, in the field of beauty is more popular than ever. Microneedling is not only widely used in the field of biomedicine, but also in the field of beauty, which has received unprecedented popularity. Microneedling is widely used in the field of beauty, and it can be used for both body contouring and skin beauty, and it also has good effects on the treatment of hair loss and scar repair; in general, the applications of microneedling in beauty can be summarized as the following: fighting skin aging, preventing and treating hair loss, weight reduction, acne treatment, cellulite removal, reduction of local accumulation of fat, dry skin ringworm, etc. The reason why “microneedling” can play an excellent beauty and skin care effect, and in the field of beauty attention, its principle can be attributed to the following two points: 1, focal damage effect: the use of micro-needle array to treat the skin, can instantly create thousands of tiny wounds on the surface of the skin, in the external stimulation, the body will repair, and cause some positive effects. 2.Micro-pore channel penetration effect: Using micro-needle array to pretreat the skin, it can create thousands of tiny channels on the skin surface in a short time, so that the beauty care products or drug active ingredients can directly reach the deeper layer of the skin through the keratin layer barrier, and the skin care products or drug active ingredients can be accurately positioned and precisely quantified to the parts that need to be repaired, improved or treated, giving full play to the drug efficacy. Based on the above principles, we can flexibly choose the drug and the size of the microneedle according to the repair area and the skin condition, so as to improve the flexibility and applicability of microneedle and achieve the purpose of treatment and maintenance efficiently and accurately. Classification of microneedles: There are many different ways to classify microneedles. For example, according to the material classification, it can be divided into silicon, metal, polymeric material microneedles, etc. Currently, microneedles are classified into hydrogel form of microneedles, hollow microneedles, biodegradable microneedles, coated microneedles, and solid microneedles based on their application in the field of drug introduction. In recent years, a variety of microneedling devices have appeared in the aesthetic plastic surgery market, such as roller microneedling, stamp microneedling, electric microneedling, DermaFrac, RF microneedling system, etc. 1, roller microneedle: currently the most widely used microneedle. Generally the main body consists of a handle and a roller, in the roller is distributed on a number of rows of micro-needles, the length is generally in 0.5 ~ 3mm, with the roller rolling on the skin, micro-needles can be formed in the skin micro-hole or stimulate skin cell proliferation. Since these microneedles are mostly made of medical grade steel, it is suitable for multiple use on a large area of skin. 2.Stamped microneedle: It consists of a handle and a stamped head, and the microneedle lies on top of the stamp, which acts vertically on the skin when used, and is generally used for local scar treatment. 3.Electric microneedle: This microneedle is divided into a pen-like body and a seal microneedle head that can vibrate. Through mechanical drive, the microneedle in the head can vibrate repeatedly, eliminating the disadvantage of uneven skin force when the operator uses the microneedle. 4.DermaFrac: A new microneedling device that combines microdermabrasion, microneedling, simultaneous deep tissue serum injection, and LED light therapy is used to treat sunburned skin, acne, enlarged pores, uneven skin tone, wrinkles, fine lines, superficial scarring, etc. 5.Radiofrequency microneedle system: With the help of microneedles, electrical energy is introduced into the subcutaneous area to treat scarring, hyperhidrosis, skin tightening, facial rejuvenation, etc. without destroying the epidermis. Tip: “Microneedling” in the field of facial rejuvenation The physical action of microneedling can be used not only to treat scarring, but also in the field of facial rejuvenation. Previously, facial wrinkle removal was performed by chemical skin peeling, which produced an inflammatory response when the epithelial layer was destroyed, resulting in collagen deposition and skin tightening. However, the treatment process that causes collagen deposition by damaging the skin’s stratum corneum barrier affects the skin’s hydration and patients often feel dry skin after the treatment. Although laser wrinkle removal is effective in improving the smoothness of the skin, because skin fibrosis makes the skin pale, the skin collagen is absorbed after a few years and fine lines reappear. In contrast, after microneedling causes minor skin damage, multiple cytokines and growth factors are released. Subsequently, fibroblasts migrate and proliferate, collagen begins to be deposited, and new blood vessels are created. With the conversion of type III collagen to type I collagen and the gradual normalization of the skin’s blood supply, the skin becomes firm and smooth, and the skin color becomes natural. Clinical anti-aging treatments using microneedling in the upper lip, forehead, eye area and other areas have achieved better results. On the one hand, microneedling can induce collagen production for “facial rejuvenation”, and on the other hand, it can further “snipe” skin aging by introducing hyaluronic acid, botulinum toxin, etc.