Skin cancer may be caused by physical and chemical stimulation, chronic inflammation stimulation, viral infection, immune factors and other factors. 1. Stimulation of physical and chemical factors: long-term sunlight exposure, ultraviolet radiation, ionizing radiation, chemical substances such as asphalt, benzo(a)pyrene, arsenic compounds, tar derivatives and other physical and chemical substances, long-term chronic stimulation will destroy the DNA structure of the skin, damage the skin’s own repair function and immune function, lead to skin gene mutation, and change to skin cancer. 2. Chronic inflammation stimulation: chronic skin ulcer, dermatitis, lupus erythematosus and other chronic inflammation stimulation may also cause skin cancer. 3. Viral infection: viral infection such as human papillomavirus may also induce skin cancer. 4. Immunity factors: Diseases such as systemic lupus erythematosus lead to abnormal immune function of the body, and the use of immunosuppressants will affect the skin’s own immune function, which will increase the possibility of skin cancer. For skin cancer, early prevention, early detection and early treatment should be carried out, and once suspected symptoms are found, go to regular hospitals as early as possible for consultation.