Erythema nevus, commonly known as “red birthmark”, is a common vascular disease with an incidence of about 3-5 per thousand. In China alone, there are more than 6 million patients, and the number of newborns is growing at the rate of about 100,000 per year. The disease is caused by dermal capillary malformation of the head, face, neck or trunk large purple erythema, progressive development of the disease with age, proliferation, nodule-like changes with bleeding and other complications, without treatment will be accompanied by a lifetime, causing a greater impact on patients and families, seriously affecting the patient’s appearance, social, work and life. Its treatment has been one of the difficulties in the treatment of vascular diseases. There are more than ten traditional treatment methods, such as radionuclide dressing, freezing, tattooing, surgical treatment, simple laser irradiation, etc., but the efficacy is not satisfactory. There are several laser systems available, but from the results concerned, it is difficult to recommend a very ideal laser system for the treatment of nevus of vivid redness. Photodynamic therapy is a therapy to destroy lesion tissue by photochemical reaction caused by specific sensitized light source radiation with the help of photosensitizer and the participation of oxygen molecules to achieve the purpose of treatment, and it is a new technology of targeted treatment that can achieve selective removal of bright red nevus without damaging normal tissues, which completely solves the problem of scarless treatment of bright red nevus that has not been solved for many years, in terms of selectivity of lesion It has made an important breakthrough in the selectivity of lesions, the accuracy of the action site, the protection of normal tissues and the treatment effect, and has achieved good clinical results. Photodynamic therapy is a new therapy with high selectivity, good efficacy, safety and reliability, which is the first choice for treating nevus. During the long-term clinical practice, we have accumulated rich experience in the diagnosis and treatment of nevus, and have gradually formed a systematic, scientific, safe and effective comprehensive treatment system integrating laser, photodynamic therapy, local injection and surgical (excision, skin implant, etc.) treatment, and the level of diagnosis and treatment is at the leading level in China, which has achieved good social and economic benefits.