Objective To analyze the effect of autologous fat transplantation combined with carbon dioxide fractional laser in the treatment of patients with hypertrophic scar after burn. Methods A total of 100 patients with hypertrophic scar after burn admitted to Xi'an Beilin LU Haijun Medical Cosmetology Clinic from February 2024 to February 2025 were selected, and they were divided into the control group and the observation group by the random number table method, with 50 patients in each group. The control group was treated with carbon dioxide fractional laser, and the observation group was treated with autologous fat transplantation combined with carbon dioxide fractional laser. The scar severity, treatment effect, Patient and Observer Scar Assessment Scale (POSAS) score and laboratory indicators were compared between the two groups. Results After treatment, the scores of scar color, thickness, vascular distribution and pliability in the observation group were lower than those in the control group (P<0.05). The total effective rate of the observation group (96.00%) was higher than that of the control group (80.00%) (P<0.05). The observer score and patient score of the observation group after treatment were lower than those of the control group (P<0.05). The level of TGF-β1 in the observation group after treatment was lower than that in the control group (P<0.05). Conclusion The application of autologous fat transplantation combined with carbon dioxide fractional laser in patients withhypertrophic scar after burn has a definite effect. It can reduce the severity of scars, improve the treatment effect, help to reduce the POSAS score, and has a stronger inhibitory effect on the expression of serum TGF-β1, which is worthy of clinical application.