A pigmented nevus is a benign neoplasm composed of nevus cells, also known as a nevus cell nevus, cellular nevus, melanocytic nevus, or nevus. They are common, occurring in almost everyone, from infancy to old age, and increase in number with age, often increasing significantly during puberty. Females tend to have more nevi than males, and whites have more nevi than blacks. They are occasionally seen on mucosal surfaces. There are various types of clinical manifestations. The color is mostly dark brown or ink-black, and a few colorless nevi have no color. Nevus pigmentosus can occur in any part of the body, affecting aesthetics, and may become cancerous, which is harmful to health. Therefore, a reasonable treatment plan should be formulated according to the size and location of the nevus, the presence or absence of signs of malignancy, and the patient’s cosmetic requirements. Surgery can be applied to any type of nevus, and pathological examination can be performed at the same time, so it is the first choice for treatment. If the following signs of malignancy appear, resection or extended resection should be carried out in time: 1, sudden increase in size and deepening of color (except during pregnancy); 2, surface erosion, ulceration, swelling, repeated infection; 3, conscious pain or itching; 4, satellite foci appear around it. In addition, those who grow on the extremities (such as palm and plantar, under the nail), mucous membranes and friction-prone areas have relatively high chances of malignant transformation, and should adopt a positive attitude towards treatment and surgical excision at the earliest possible time. Non-surgical treatment has the advantage of avoiding the pain of surgery, but the indications are more limited, and it can be applied to those with a diameter of <1MM. Commonly used methods include laser, freezing and so on. However, repeated physical and chemical stimulation can easily induce malignant changes, and those who are not completely treated by this method should be promptly excised and sent for examination. Generally speaking, the treatment of pigmented nevus should adhere to the principle of "if not treated, the treatment must be thorough".