Acne is an inflammatory disease caused by the infection of Propionibacterium acnes, which is also associated with the high secretion of sebaceous glands. After performing red and blue light treatment, blue light irradiation can kill the Propionibacterium acnes in acne and also inhibit the secretion of sebaceous glands, thus causing the inflammatory response of acne to subside. Red light irradiation can penetrate the skin surface tissues and induce the cells to secrete collagen, which can play a role in removing acne marks and repairing acne scars. There is a synergistic effect between the two common irradiation, but if due to improper operation or not pay attention to care, the following risks may arise: 1. Skin damage: After the end of red and blue light treatment, it may lead to erythema, pigmentation, skin phototoxic reaction, photosensitivity reaction and skin tumor. Therefore, go out to apply moisturizing sunscreen, strictly prohibit the use of aloe vera, aspirin and alcohol, including cosmetics containing alcohol, do not squeeze, rub the treatment surface; 2, skin allergy: manifested as skin erythema, itching, etc., need timely medical treatment; 3, dry skin: after the end of treatment, the skin’s absorption capacity is enhanced, metabolism accelerated, some patients may appear dry skin, dehydration. After the end of the surgery, the skin should be cared for to replenish sufficient moisture and nutrition; 4. Superficial scar formation, pigmentation, pigment loss, and abnormal skin sensation.