To observe the therapeutic effect of scar internal separation surgery combined with fractional carbon dioxide laser in the treatment of facial depressed scars. Methods A total of 80 patients with facial depressed scars admitted to Changjiang Hospital of Changjiang Water Resources Commission and Central South Hospital of Wuhan University from January 2020 to January 2023 were selected as the research objects. According to different treatment measures, they were divided into control group and study group, with 40 patients in each group. The control group was treated with fractional carbon dioxide laser, and the study group was treated with scar internal separation surgery combined with fractional carbon dioxide laser. The clinical acne scar assessment scale (ECCA) weight score, clinical efficacy, scar area, pigmentation area and adverse reactions were compared between the two groups. Results After treatment, the ECCA weight score of the two groups was lower than that before treatment, and that in the study group was lower than that in the control group (P <0.05). The total effective rate of treatment in the study group was 95.00%, which was higher than 80.00% in the control group (P <0.05). After treatment, the scar area and pigmentation area of the two groups were smaller than those before treatment, and those in the study group were smaller than those in the control group (P <0.05). The incidence of adverse reactions in the study group was 15.00%, which was lower than 30.00% in the control group (P <0.05). Conclusion The application of Scar internal separation surgery combined with fractional carbon dioxide laser in the treatment of facial depressed scars is beneficial to reduce the scar area, reduce pigmentation, improve the nature and density of acne scars, and has high safety, which is worthy of clinical application.