Photodynamic Diagnosis and Therapy (PDD, PDT) is a new technology for disease diagnosis and treatment using photodynamic effect, i.e., photosensitization reaction with the participation of singlet oxygen. The PDD&PDT technique consists of two steps, firstly, a certain dose of photosensitizer is given to the target tissue, and according to the characteristic that the abnormal hyperplastic tissue can selectively absorb and retain the photosensitizer, the lesioned tissue is irradiated with laser of specific wavelength, and the photosensitizer undergoes a series of photochemical and photobiological reactions, emitting fluorescence of specific wavelengths to distinguish the abnormal hyperplastic tissue from the normal tissue; at the same time, the photosensitization reaction generates monoclinic oxygen and releases prostaglandin. state oxygen, releasing cytokines such as prostaglandins, lymphokines and thromboxanes, which destroy the microvasculature of the target tissue and the biofilm of the target cells, thus leading to apoptosis and achieving the therapeutic effect of removing the abnormal hyperplastic tissue. In the 1950s, photodynamics began to be used in the early diagnosis of tumors, forming the “tumor fluorescence localization diagnosis technology”, marking the clinical practical stage of photodynamic diagnosis and treatment technology; the development of hematoporphyrin derivatives (HPD) in the same period was a key progress in the field of photosensitizer research, which played a crucial role in the development and popularization of PDT. In the 1960s, ruby lasers were introduced to improve the effect of photodynamic therapy, and in the 1990s, with the approval of the first photosensitizer PHOTOFRIN in the United States, Canada, the European Union and Japan, research, development and application in this field were active. Currently photodynamic is widely used in the diagnosis and treatment of skin tumors and precancerous lesions, warts, acne, early proliferative scarring, and bright red nevus. Among them, the process of skin tumor early diagnosis and treatment: drug preparation → disinfection → drug application for 3h → photodynamic circling of early tumor proliferative tissue area → formulation of treatment plan, such as photodynamic 20min.