Objective To analyze the effect of CO2 fractional laser in repairing depressed acne scars. Methods A total of 118 patients with depressed acne scars admitted to our hospital from February 2021 to February 2022 were randomly divided into control group and observation group, with 59 patients in each group. The control group was treated with laser grinding, and the observation group was treated with CO2 fractional laser. The scar area, Echelle d'Evaluation Clinique des Cicatrices d'Acne (ECCA) and complications were compared between the two groups. Results After treatment, the scar area of the observation group was smaller than that of the control group, the difference was statistically significant (P <0.05). After treatment, the ECCA score of the observation group was lower than that of the control group, the difference was statistically significant (P <0.05). The incidence of adverse reactions in the observation group was 1.69%, which was lower than 15.25% in the control group, the difference was statistically significant (P <0.05). Conclusion CO2 fractional laser is effective in repairing depressed acne scars, which can effectively reduce the scar area of patients and reduce the severity of acne scars. Meanwhile, the risk of adverse reactions after repair is low and the application safety is high.