Objective To explore the clinical effect of red and blue light therapeutic apparatus in the treatment of patients with mild to moderate facial acne. Methods A total of 86 patients with mild to moderate facial acne diagnosed and treated in our hospital from January to December 2022 were randomly divided into control group and observation group, with 43 patients in each group. The control group was treated with electric ion therapy on the basis of conventional western medicine treatment, while the observation group was treated with red and blue light therapy apparatus on the basis of the control group. The clinical efficacy, skin lesion score, skin index and adverse reactions were compared between the two groups. Results The total effective rate of clinical treatment in the observation group was 95.35%, which was higher than 79.07% in the control group (P<0.05). The scores of skin lesions in the observation group were better than those in the control group (P<0.05). The heme content, skin surface pH value and transepidermal water loss in the observation group were better than those in the control group (P<0.05). The incidence of adverse reactions in the observation group was 6.98 %, which was lower than 23.26 % in the control group (P<0.05). Conclusion The application of red and blue light therapeutic apparatus in the treatment of patients with mild to moderate facial acne can effectively improve the therapeutic effect, improve the skin condition, reduce skin lesions and reduce the incidence of adverse reactions