Laser vaporization of nevus nigricans too deep is the most common cause of local scar formation after wound healing. When treating nevus pigmented deep in the dermis, care should be taken to avoid laser vaporization in a direction perpendicular to or at a greater angle to the skin line. Otherwise, a more obvious concave scar will be formed. Giant nevus and keloid should not be removed by laser vaporization. For nevus cells located in the deep dermis, it is recommended to treat the nevus in several times, and splitting treatment can achieve the effect of flat skin without scarring. After the epidermal damage of the skin, the local cell metabolism is enhanced, and new cells are continuously produced to supplement the constantly dead and shed cells to repair the trauma. Through clinical observation, when the epidermal cells migrate upward for local epidermal repair, the deep mole tissues also gradually migrate to the superficial layer of the skin, and when the mole tissues reach the epidermis, the next treatment can be carried out, and satisfactory results can be obtained through multiple treatments. If patients ask for complete removal of nevus tissue at one time, they must be informed of the consequences of leaving concave scarring.