Objective To investigate the effect of free supracarpal perforator flap of ulnar artery with tendon in the repair of small and medium-sized dorsal digital skin and soft tissue combined with extensor tendon defect. Methods A total of 60 patients with small and medium-sized dorsal digital skin and soft tissue combined with extensor tendon defect treated in People′s Hospital of Heshan City from January to October 2020 were selected as the research objects.They were divided into the research group and the control group according to random number table method, with 30 cases in each group. The control group was repaired with composite flap, the research group was treated with free supracarpal perforator flap of ulnar artery with tendon. The perioperative indexes, clinical efficacy and complications 12 months after operation were compared between the two groups. Results The operative time, time to get out of bed for the first time and length of hospital stay in the research group were shorter than those in the control group. The intraoperative blood loss in the research group was less than that in the control group, the excellent and good efficacy rate 12 months after operation in the research group was higher than that in the control group, the total complication rate 12 months after operation in the research group was lower than that in the control group, the differences were statistically significant (P＜0.05). Conclusion The repair of free supracarpal perforator flap of ulnar artery with tendon is simple and has few postoperative complications, which can effectively improve the extension and flexion function of fingers in patients with small dorsal digital skin and soft tissue combined with extensor tendon defect.