How can acne be treated quickly, safely and effectively? Current traditional treatments have limitations. The effects of medication vary from person to person, and long-term use can easily lead to drug resistance and potential toxic side effects. For patients who cannot tolerate medication or do not want to accept medication, physical therapy is the best choice. Currently, light therapy is an emerging therapy among the commonly used physical therapies, mainly visible light therapy, photodynamic therapy and laser therapy. Relative to drugs, phototherapy has the advantages of fast onset of action, short course of treatment, and few adverse reactions. Photodynamic therapy is a new technology that has been developed in recent years as a safe and effective non-invasive treatment for acne, especially moderate to severe acne. Photodynamic therapy uses specific wavelengths of light to activate the porphyrins metabolized by Propionibacterium acnes, and through phototoxic reactions, induces cell death and stimulates the release of cytokines from macrophages to promote the self-healing of lesions. It inhibits the secretion of sebaceous glands, reduces follicular obstruction, reduces the number of pimples and inflammatory lesions, and directly kills Propionibacterium acnes to achieve the goal of treatment. Its treatment advantages are significant and non-invasive, rapid, effective, well tolerated by patients, and with few systemic side effects.