To analyze the efficacy and safety of 30% salicylic acid combined with red and blue light in the treatment of facial mild to moderate acne. Methods A total of 90 patients with mild to moderate acne admitted to the dermatology department of our hospital from August 2021 to April 2023 were randomly divided into control group and study group, with 45 patients in each group. The control group was treated with 30% salicylic acid, and the study group was treated with red and blue light on the basis of the control group. The clinical efficacy and adverse reactions of the two groups were compared. Results The total effective rate of treatment in the study group was 86.67%, which was higher than 64.44% in the control group, and the difference was statistically significant (P <0.05). The incidence of adverse reactions in the study group was 44.44%, which was slightly higher than 40.00% in the control group, but the difference was not statistically significant (P >0.05). Conclusion Red and blue light combined with supramolecular salicylic acid in the treatment of mild to moderate acne is more effective, with mild adverse reactions and high patient acceptance, which is worthy of clinical application.