Pigmented nevi, also referred to as nevus, nevus or nevus, are benign tumors of the skin most commonly composed of normal pigment-containing nevus cells and occasionally seen on the surface of mucous membranes. There are various types of clinical manifestations. Most of them are dark brown or inky black in color, and there are also colorless nevi without color. Such as intradermal nevus, junctional nevus, mixed nevus, etc. There are also giant nevus, blue nevus, juvenile melanoma, etc. Some types can become malignant under certain conditions and deserve attention. Pigmented nevi mostly occur on the face, neck and back and can be seen in any normal human body. They may be present at birth or may appear gradually in the early postnatal years. Most grow slowly or persist for many years without change, but spontaneous regression rarely occurs. Surgical and non-surgical treatments are available. The treatment is effective. Pigmented nevi are congenital benign tumors composed of pigmented cells, most of which are benign; in later stages, there are malignant cases. Once a pigmented nevus becomes malignant, its malignancy is extremely high and its metastasis rate is the fastest, and the treatment is not ideal. The disease can be seen in all parts of the skin, with the face and neck, chest and back being the preferred sites. A few occur in the mucous membranes, such as the oral cavity, labia, and lid conjunctiva. For certain pigmented nevi that have a high incidence of junctional nevi and those with signs of malignant transformation, timely excision is required.