Objective To explore the effect of 2940 nm erbium laser grinding combined with ultra-pulsed carbon dioxide fractional laser treatment on skin indexes for patients with facial acne scar. Methods A total of 66 patients with facial acne scar admitted to the Department of Cosmetic Dermatology, Dermatology Hospital of Guangxi Zhuang Autonomous Region from January 2023 to April 2024 were selected as the research subjects. According to the random number table method, they were divided into the control group and the observation group, with 33 patients in each group. The control group was treated with ultra-pulsed carbon dioxide fractional laser alone, and the observation group was treated with 2940 nm erbium laser grinding combined with ultra-pulsed carbon dioxide fractional laser. The clinical efficacy, symptom scores, skin indexes and treatment satisfaction were compared between the two groups. Results The total effective rate of treatment in the observation group was 96.97%, which was higher than 78.79% in the control group (P <0.05). After treatment, the scores of thickness, softness, color and blood vessel distribution in the two groups were lower than those before treatment, and those in the observation group were lower than those in the control group (P <0.05). After treatment, the pore index, erythema index texture index and spot index in two groups were lower than those before treatment, and those in the observation group were lower than those in the control group (P <0.05). The treatment satisfaction rate in the observation group was 96.97%, which was higher than 75.76% in the control group (P <0.05). Conclusion The application of 2940 nm erbium laser grinding combined with ultra-pulsed carbon dioxide fractional laser for the treatment of facial acne scar can effectively relieve clinical symptoms, improve skin indexes, and enhance the clinical efficacy and treatment satisfaction.