Objective To analyze the application value of red and blue light therapeutic instrument in the diagnosis and treatment of acne. Methods A total of 82 patients with acne admitted to our hospital from March 2022 to April 2023 were selected as the research objects. According to the random number table method, they were divided into reference group and study group, with 41 patients in each group. The reference group was treated with conventional drugs, and the study group was treated with red and blue light therapeutic apparatus on the basis of the reference group. The symptom scores, adverse reactions, treatment effects and satisfaction of the two groups after treatment were compared. Results The total effective rate of the study group was 97.56%, which was higher than the reference group was 78.05% (P <0.05); The satisfaction rate of the study group was 100.00%, which was higher than 80.49% of the reference group (P <0.05); After treatment, the scores of various symptoms such as acne, pustules, papules, and itching in the study group were lower than those in the reference group (P <0.05); The incidence of adverse reactions in the study group was 4.88%, which was lower than the reference group was 24.40% (P <0.05). Conclusion The red and blue light therapeutic apparatus has a good effect on acne. It can not only improve the problem of facial acne, but also reduce the incidence of adverse reactions and improve patient satisfaction. It is worthy of clinical application.