Moles, also known as “melanocytic nevi”, are benign proliferations of melanocytes; according to the different parts of their growth, they are classified as pigmented nevi, epidermal nevi, and sebaceous nevi. The increasing number of small melanocytic nevi on the face may be related to genetic factors, environmental factors and so on. 1. Genetic factors: In the process of nevus growth, the influence of family genetic factors is more common. Clinically, it is found that patients who have more moles on their faces have more moles on their parents and other immediate family members. Genetic factors play an important role in the early stage of nevus formation, while the later stage is mainly influenced by environmental factors. 2. Environmental factors: If patients are exposed to ultraviolet radiation, trauma, physical or chemical stimulation, immunosuppression and other factors for a long period of time, it is very easy to stimulate the proliferation of melanocytes. Usually, ultraviolet light is one of the most important factors affecting the formation of nevus, and its mechanism of action is to induce melanocytes to undergo gene mutation, induce proliferation, and then prompt melanocytes to gather and form melanocytic nevus. It is well known that heredity cannot be changed, and patients need to avoid risk factors in environmental factors to minimize the production of nevi, such as paying attention to sun protection and avoiding the use of irritating chemical skin care products. This disease generally does not require treatment; when patients have concerns such as aesthetic appearance, or when it rapidly increases in size and color, it can be removed by laser or surgery. It is recommended that patients with sudden and dramatic growth of nevus should go to the hospital in time to complete the relevant examinations, clarify the cause of the disease, and follow the doctor’s instructions for treatment.