Objective To observe the efficacy and safety of carbon dioxide fractional laser in the treatment of acne scar. Methods A total of 80 patients with acne scar admitted to Pingyi County Hospital of Traditional Chinese Medicine from June 2021 to June 2024 were selected as the research subjects. They were divided into control group and observation group according to the random number table method, with 40 patients in each group. The control group was treated with conventional drugs, and the observation group was treated with carbon dioxide fractional laser. The clinical efficacy, symptom improvement time, scar area, pigmentation area and adverse reactions were compared between the two groups. Results The total effective rate of the observation group was 95.00%, which was higher than 75.00% of the control group (P <0.05). The descrustation time, edema duration and pigmentation duration of the observation group were shorter than those of the control group (P <0.05). After treatment, the scar area and pigmentation area of the observation group were better than those of the control group (P <0.05). The incidence of adverse reactions in the observation group was 5.00%, which was lower than 15.00% in the control group (P <0.05). Conclusion The implementation of carbon dioxide fractional laser treatment for patients with acne scar can rapidly improve their clinical symptoms and enhance the overall treatment effect, and the treatment safety is high, which is worthy of clinical application.