Objective To explore the efficacy of type A botulinum toxin injection combined with ultra-pulsed carbon dioxide fractional laser in the treatment of hypertrophic scar. Methods A total of 80 patients with hypertrophic scar admitted to our hospital from January 2022 to December 2023 were selected as the research subjects. According to different treatment schemes, they were divided into group A and group B, with 40 patients in each group. Group A was treated with ultra-pulsed carbon dioxide fractional laser, and group B was treated with type A botulinum toxin injection combined with ultra-pulsed carbon dioxide fractional laser. The scar condition, treatment effect, serum inflammatory factor levels and adverse reactions were compared between the two groups. Results After treatment, the scores of color, thickness, vascular distribution, softness, and total score in group B were lower than those in group A, and the levels of IL-1β and TNF-α were lower than those in group A (P<0.05). The total effective rate of treatment in group B (97.50%) was higher than that in group A (80.00%), and the incidence of adverse reactions was higher than that in group A (P <0.05). Conclusion For patients with hypertrophic scar, type A botulinum toxin injection combined with ultra-pulsed carbon dioxide fractional laser can improve the treatment effect, reduce scar severity, and lower serum inflammatory factor levels. Although the incidence of adverse reactions increases, they are all mild and tolerable to patients.