Objective To explore the clinical effect of poly-L-lactic acid combined with PicoSure laser in the treatment of acne depressed scars. Methods A total of 48 patients with acne depressed scars who were treated in Xiamen Siming Jiguang Aesthetic Medical Beauty Clinic from January 2019 to December 2020 were selected as the research objects. They were divided into control group and observation group by random number table method, w ith 24 patients in each group. The control group was given PicoSure laser, and the observation group was given local injection of poly-L-lactic acid first, followed by PicoSure laser. The clinical efficacy, treatment satisfaction and adverse reactions of the two groups were compared. Results The total effective rate of treatment in the obs ervation group was 95.83%, which was higher than 87.50% in the control group, and the difference was statistically significant (P <0.05). The satisfaction of the observation group was higher than that of the control group, and the difference was statistically significant (P <0.05). The incidence of adverse reactions in the observation group was 12.50%, which was slightly higher than 8.33% in the control group, but the difference was not statistically significant (P >0.05). Conclusion Poly-L-lactic acid combined with PicoSure laser is effective in the treatment of acne depressed scars, which can improve patient satisfaction and is well tolerated. Meanwhile, it will not increase the incidence of adverse reactions and is worthy of clinical application.