Usually, nevus of melanin sees the dermatologist and is related to congenital development, ultraviolet radiation and other reasons, and appears as dark-colored round or oval papules and nodules. Melanotic nevus is a benign neoplasm containing melanocytes, which belongs to benign tumors, usually, melanotic nevus needs to see dermatology. Clinical studies have shown that the occurrence of nevus melanosus is related to congenital developmental defects, and also related to acquired factors such as ultraviolet irradiation, trauma, immunosuppression, and hormone level changes. Nevus pigmentosus mainly manifests as round or ovoid, looks like papule or nodule, sometimes can be slightly protruding from the skin surface, can be hairy or hairless, and the color is mostly gray, brown or black. Generally, patients do not have other self-conscious discomfort symptoms, so there is no need for treatment. However, if the nevus suddenly increases in size, itching and pain, accompanied by a burning sensation, it is necessary to consider the possibility of malignant transformation. It is recommended that patients with nevi maintain a good attitude and go to the hospital in time if there is any obvious discomfort.