Objective To explore the effect of Qingfei Xiaocuo decoction combined with red and blue light therapy on TCM syndrome score and skin barrier function in patients with acne of lung-stomach heat excess syndrome. Methods A total of 90 patients with acne of lung-stomach heat excess syndrome admitted to Wuxi Traditional Chinese Medicine Hospital from November 2024 to August 2025 were selected, and they were divided into the control group and the study group by the random number table method, with 45 patients in each group. The control group was treated with Qingfei Xiaocuo decoction, and the study group was treated with Qingfei Xiaocuo decoction combined with red and blue light therapy. The clinical efffcacy, TCM syndrome score and skin barrier function were compared between the two groups. Results The total effective rate of treatment in the study group (95.56%) was higher than that in the control group (80.00%) (P<0.05). The TCM syndrome score of the two groups after treatment was lower than that before treatment, and that of the study group was lower than that of the control group (P<0.05). The stratum corneum moisture content and R2 of the two groups after treatment were higher than those before treatment, and those in the study group were higher than those in the control group (P<0.05). The TEWL of the two groups after treatment was lower than that before treatment, and that of the study group was lower than that of the control group (P<0.05). Conclusion Qingfei Xiaocuo decoction combined with red and blue light therapy has a deffnite effect in the treatment of acne of lung-stomach heat excess syndrome, which can not only effectively improve the clinical symptoms of patients, but also enhance their skin barrier function, and is worthy of clinical application.