The use of laser to remove pigment is the principle of laser light explosion. The skin is irradiated by a fixed wavelength laser. The laser penetrates the epidermis and dermis papillary layer and acts on the micro-pigments in the skin. The pigments expand and burst when they absorb the energy of the laser. Some of the pigments (in the superficial epidermis) will act because they lose the protective effect of the protein fibers. That is to say, part of the body (in the basal layer) will be swallowed by macrophages in the body, and then discharged from the body with the human lymphatic system. The pigments of the diseased tissues will gradually fade until they disappear, while the surrounding normal skin will not cause any damage due to the absence of absorption of fixed wavelength laser.