Nevus flammeus, also known as port-wine stains (PWS), is a common congenital, benign, superficial dermal capillary dilation malformation that does not fade on its own. The pathogenesis is still unclear, but some studies have shown that the distribution of nerves in the lesion area is significantly reduced compared with the normal side of the skin, and the reduced neurovascular ratio may lead to vasodilatation malformation, which may be an important factor in its pathogenesis. Dilated malformation of capillary network lumen in the papillary layer of the dermis and increased number of blood cells per unit area in the superficial layer of the skin result in abnormal red or purplish-red color of the skin. The clinical manifestation is a flat, well-defined pink plaque that is present at birth and increases in size with age and growth, deepening to red and purple in color, thickening of the tumor, and nodule-like changes in some cases, and in a few cases the hyperplastic nodules may be grape-like or verrucous, or even extremely dilated and drooping. They rarely resolve spontaneously and will generally remain with the patient for life without treatment. The incidence of this disease is as high as 3-5 per 1,000, and it can occur anywhere in the body, but it is more common in the face and neck, accounting for 75%-80% of the cases, and because it occurs in exposed parts of the body, it has a serious impact on patients’ psychology and quality of 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 relevant results, it is difficult to recommend a very ideal laser system to treat nevus of vivid redness. At present, our department mainly adopts integrated treatment methods such as laser, photodynamic and surgery. Photodynamic therapy is to use laser photosensitization technology to precisely select the capillary network of superficial dermal lesions of nevus of bright redness, which can eliminate the lesions while protecting the normal tissues of the skin to the maximum extent, and is a new treatment for nevus of bright redness with high selectivity, good efficacy, safety and reliability. At present, our department has achieved good clinical effect by using this treatment method, which is better than the traditional laser treatment method in general. The characteristics of photodynamic therapy in the treatment of nevus of bright redness: ① Precisely and selectively damage the capillary network in the superficial layer of the dermis that expands and deforms. ② Scarless treatment, without damaging the epidermis and deep dermis. ③ Low toxicity, safe, and can be repeatedly treated. ④ Short treatment time and convenient disposal. ⑤ Stable and reliable therapeutic effect. Once the dilated and deformed capillary network of bright red nevus is destroyed by PDT treatment, it is difficult to repair and regenerate, and the possibility of recurrence is very small.