Carbon dioxide laser is a traditional laser with a history of 50 years ago, but the traditional laser has disadvantages such as large damage, long recovery time and many side effects because it does not have fractional mode. Fractional technology was introduced in 2006, and its theory originated from the Fractional Photothermolysis theory (Fractional Photothermolysis) proposed by Rox Anderson, an expert in photomedicine at Harvard University in 2004, which is an expansion and leap forward of the traditional Selective Fractional Photothermolysis is an expansion and leap forward from the traditional Selective Photothermolysis. It can meet the treatment requirements of different patients and different diseases to the maximum extent, because the fractional laser equipment has various adjustable parameters, such as: adjustable spot diameter, adjustable treatment density, adjustable treatment depth, adjustable treatment energy, so that different diseases can get personalized treatment plan, so as to obtain the best therapeutic effect, which is the real meaning of using fractional treatment, the essence of fractional is The essence of fractional treatment is to achieve maximum efficacy while minimizing recovery time and side effects. The fractional CO2 laser is a gas laser, the principle of action is “focal photothermal action”, through the fractional laser to produce an array of tiny beams, after the action of the skin to form a number of three-dimensional columnar structure of the tiny thermal damage area, each tiny damage area is surrounded by undamaged normal tissue, its keratinocytes can quickly crawl, so that it heals quickly. It can make the collagen fibers and elastic fibers proliferate and rearrange, so that the content of type I and III collagen fibers is close to the normal ratio, so that the structure of the pathological scar tissue is changed, and gradually softens and regains elasticity. The main absorbing group is water, which is precisely the main component of the skin. It can cause the dermal collagen fibers to contract and denature when heated, and induce a trauma healing reaction in the dermis, resulting in the orderly deposition of collagen and promoting collagen proliferation, thus improving skin elasticity and reducing scarring. The clinical characteristics are: the efficacy of scar treatment is comparable to that of plastic surgery, but less invasive, shorter recovery time, less side effects, and more acceptable to patients.