Objective To observe the effect of combined treatment of photorejuvenation and collagen dressing in patients with acne and pigmentation in the late stage. Methods From January 2023 to June 2024, 68 patients with acne and pigmentation in the late stage of acne who were treated in the Department of Dermatology and Cosmetology of Mulan Qingyan Medical Cosmetology Clinic in Suzhou Industrial Park were selected as the research objects. They were divided into conventional group and study group by random number table method, with 34 patients in each group. The conventional group was treated with photorejuvenation, and the study group was treated with photorejuvenation combined with collagen dressing. The clinical efficacy, improvement of acne and pigmentation, clinical related indicators, skin color and adverse reactions were compared between the two groups. Results The total effective rate of treatment in the study group was 97.06%, which was higher than 79.41% in the conventional group (P <0.05). After treatment, the scores of acne marks and pigmentation in the study group were lower than those in the conventional group (P <0.05). After treatment, the scab healing time, swelling duration and downtime in the study group were shorter than those in the conventional group (P <0.05). After treatment, the levels of porphyrin and spots in the study group were lower than those in the conventional group (P <0.05). The incidence of adverse reactions in the study group was 2.94%, which was lower than 23.53% in the conventional group (P <0.05). Conclusion The combination of photorejuvenation and collagen dressing is effective in the treatment of acne and pigmentation in the late stage of acne, which can effectively improve the acne and pigmentation of patients, shorten the recovery time, reduce the severity of acne scars, and improve the skin color. Meanwhile, the incidence of adverse reactions is low, the safety is high, and it is suitable for clinical application.