Study to Evaluate the Efficacy, Safety and Tolerability of Photodynamic Therapy(PDT) With Chlorin-e6 in Treating Moderate to Severe Acne

Inclusion Criteria: 1. Subject is male or non-pregnant female 18 years of age and younger than 50 years of age. 2. Subject has moderate to severe facial acne vulgaris. 3. Subject has provided written informed consent. Exclusion Criteria: 1. People who are taking photosensitive drugs; 2. Allergic to any component of the photosensitizer; 3. porphyrins or allergies to porphyrins, with a history of photosensitivity; 4. Pregnant or lactating women and those planning to become pregnant within 3 months; 5. Oral or topical antibiotics, retinoids, glucocorticoids, peroxybenzoyl and other drugs within the past 1 month; 6. Have a history of exposure to sunlight in the past 1 month, have received photoelectric treatment in the past 3 months, or have received facial grinding treatment in the past six months; 7. are using vasodilators (such as nitroglycerin, etc.), beta blockers (such as metoprolol, etc.), anticoagulants (such as warfarin, etc.) and other drugs that easily cause facial capillary dilatation; 8. Patients with facial rosacea, atopic dermatitis, hormone-dependent dermatitis and other facial skin-related diseases; 9. Abnormal blood and urine routine, liver and kidney function, diseases of important organs and hematopoietic system that researchers believe are not suitable for clinical trials; 10. Patients participating in other clinical trials at the same time.