Objective To evaluate the efficacy and safety of CO? fractional laser combined with corticosteroid injection in the treatment of hypertrophic scar. Methods A total of 100 patients with hypertrophic scar admitted to the Department of Dermatology, Baoji People's Hospital from August 2023 to October 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 50 patients in each group. The control group received single corticosteroid injection treatment, and the observation group received CO? fractional laser combined with corticosteroid injection. The skin lesions, clinical efficacy, scar thickness, blood perfusion, inflammatory factor levels, adverse reactions and recurrence rate were compared between the two groups. Results The mVSS score of the observation group after treatment was lower than that of the control group (P <0.05). The total effective rate of treatment in the observation group (96.00%) was higher than that in the control group (80.00%) (P <0.05). After treatment, the scar thickness in the observation group was thinner than that in the control group, and the blood perfusion was less than that in the control group (P <0.05). The levels of IL-1β, IL-6, and TNF-α in the observation group after treatment were lower than those in the control group (P <0.05). The incidence of adverse reactions in the observation group was lower than that in the control group, but the difference was not statistically significant (P >0.05). The recurrence rate of the observation group (0) was lower than that of the control group (8.00%) (P <0.05). Conclusion CO? fractional laser combined with corticosteroid injection has an ideal overall effect in the treatment of hypertrophic scar, which can effectively improve scar, promote lesion elimination, and has good safety and low recurrence rate, with high application value.