:Objective "To explore the therapeutic effect of local 5-aminolketovalerate photodynamic therapy in the treatment of moderate and severe acne". Methods: Fifty patients with moderate and severe acne treated in our hospital from December 2022 to December 2023 were divided into two groups: control group: red and blue light irradiation treatment, and study group: local 5-amino-ketovaleric-photodynamic therapy. The clinical efficacy, skin lesions and inflammatory factors of the two groups were analyzed. Results: Compared with the control group, the clinical efficacy of the study group was higher (P<0.05); Compared with the control group, the study group had fewer inflammatory and non inflammatory skin lesions (P<0.05); Compared with the control group, the study group had lower levels of IL-8, TNF - α, and CRP (P<0.05).Conclusion: Local 5-amino-ketovalerate photodynamic therapy can reduce the number of skin lesions and the level of inflammatory factors in moderate and severe patients, and the effect is significant.