Objective To explore the effect of free flap transplantation in hand function and aesthetic reconstruction after burn. Methods A total of 108 patients with hand burn admitted Ningxia Hui Autonomous Region the No.1 People's Hospital of Shizuishan from June 2023 to January 2025 were selected, and they were divided into the control group and the observation group by the random number table method, with 36 patients in each group. The control group was treated with traditional flap transplantation, and the observation group was treated with free flap transplantation. The hand function, aesthetic reconstruction effect and complication rate were compared between the two groups. Results After intervention, the pinch times between index finger and thumb, TAM and Carroll Hand Function Test score in the two groups were higher than those before intervention, and those in the observation group were higher than those in the control group (P <0.05). After intervention, the scores of skin color, pain, status, and aesthetics in the two groups were higher than those before intervention, and those in the observation group were higher than those in the control group (P <0.05). There was no significant difference in the incidence of complications between the two groups (P >0.05). Conclusion The application effect of free flap transplantation in hand function and aesthetic reconstruction after burn is good, which can effectively restore hand function, help to improve aesthetic reconstruction effect, and will not increase the incidence of complications. It worthy of clinical application.