Mole is a common pigmented mole that appears on the exposed part of the face and has a great impact on the patient’s image, so many patients seek various treatments for moles and are also eager to understand the causes of the formation of moles. The formation of nevus is mainly caused by the abnormal increase and accumulation of melanin particles secreted by melanocytes or melanocytes in the skin. Commonly, nevus is formed by the accumulation of melanocytes into nests or clusters; while in nevus of Ota and freckle-like nevus, the increased melanocytes are scattered and can present different colors due to their different distribution shades. There are many reasons for the formation of nevus, which can be present at birth or can occur later in life. Some people are born with them, while many others are formed later in life. Some moles grow on the face and seriously affect the patient’s appearance and mental state, which can be removed and prevented by many methods. There are three types of nevi: junctional nevi, mixed nevi, and intradermal nevi. Among them, junctional nevus and intradermal nevus are very likely to cause malignant melanoma, and according to incomplete statistics, one in every 100,000 people will have malignant lesions. Moreover, with the pollution of the atmosphere, the destruction of the ozone layer and computer radiation, the chance of nevus lesions is increasing. In order to enhance the knowledge of nevus lesions and raise awareness of prevention. The formation of nevus itself is a type of nevus, which often attracts special attention because of its localized darkness, rough and raised skin, and short hard hairs. Moles that occur in areas of the body that are susceptible to friction or injury should be taken seriously, such as moles that grow rapidly and grow larger, become lighter or darker and brighter, lose the short hairs on the mole, become red around the mole, vaguely visible as blood, and have broken crusts or even form long-lasting ulcers on the surface. If the lymph nodes nearby are swollen, or some small satellite-like moles appear around a large mole, it indicates that the mole has the tendency to become malignant, and should be diagnosed by dermatologists and surgeons at hospitals for timely treatment.