Nevus pigmentosus, also referred to as nevus pigmentosus, nevus pigmentosus or nevus nigra, is the most common benign tumor of the skin composed of normal pigment-containing nevus cells. Ordinary acquired nevus does not require treatment, and small lesions can be treated with super-pulse CO2 laser. If the nevus occurs in the parts which are easy to be rubbed and damaged, or if there is no evidence of malignancy in the larger nevus on the face, it is better to perform surgical excision, which can be partially excised in stages or completely excised, and when completely excised, it is possible to carry out transfer of neighboring flaps or free skin grafting. If malignancy is suspected, surgical excision should be used for biopsy. Pigmented nevus can also be malignant. If a nevus suddenly grows in size, nodules appear and its color deepens in a short period of time, one should be vigilant. If the nevus keeps expanding outward, the boundary is blurred, even pseudopods appear, when it expands to a certain extent, papillary proliferation or breakage occurs, forming small ulcers, the surface is easy to bleed, ooze, or covered with bloody crusts, and black dots, black halos, or hyperpigmented nodules often appear around the nevus, and lymph nodes of the area near the nevus are often enlarged, and they can be palpated. Patients also feel localized tingling, burning and painful discomfort. At this time, one should immediately seek medical attention and take biopsy pathology section for examination in order to make a clear diagnosis.