Acne, commonly known as “pimples,” is a chronic inflammatory skin disease that occurs in adolescents, with an incidence of over 80%. The causes of acne are related to the rapid development of sebaceous glands and overproduction of sebum due to the elevated level of sex hormones in the body during puberty, as well as to the structure of the diet and the lack of micronutrients in the body. Incorrect treatment measures can also lead to the aggravation of acne. If acne is not treated in a timely manner, it is easy to leave scars that are difficult to heal for life, affecting aesthetics and having a more serious negative impact on the psychology and life of adolescents. Serious cases lead to mental health problems, commonly resulting in impaired self-esteem and self-confidence, embarrassment, depression and nervousness, leading to social barriers and affecting employment. Photodynamic is the latest technology for the treatment of acne originating from Europe and the United States. It is a new technology that uses photodynamic reactions for disease diagnosis and treatment based on the interaction of light, photosensitizers and oxygen, and a large number of research reports at home and abroad confirm that photodynamic therapy is a new technology for the physical treatment of acne that is highly efficient, fast and well tolerated. The advantages of photodynamic therapy for acne: 1. Directly targeting the cause of acne, multi-path synchronous action, significant efficacy and long-lasting effect. 2. Local topical treatment, no systemic toxic side effects. 3. Long-term inhibition of sebum secretion, not easy to recur after healing. 4.Promote skin repair and prevent scar formation. 5.Photodynamics has the best efficacy on inflammatory papules, and one treatment will make the lesions subside significantly.