Objective To explore the effect of free flap repair on flap survival rate, joint function recovery and pain degree in patients with skin and soft tissue defect of the extremities. Methods A total of 60 patients with skin and soft tissue defect of the extremities admitted to our hospital from January 2020 to January 2023 were selected as the research subjects. They were divided into conventional group and experimental group by the random number table method, with 30 patients in each group. The conventional group was treated with conventional wound repair, and the experimental group was treated with free flap repair. The flap survival rate, joint function recovery, pain degree, treatment effect and treatment-related indicators were compared between the two groups. Results The flap survival rate and Kphoed joint function score of the experimental group were higher than those of the conventional group, and the VAS score was lower than that of the conventional group (P <0.05). The total effective rate of treatment in the experimental group was 96.67%, which was higher than 73.33% in the conventional group (P <0.05). The frequency of dressing change, operation preparation time, antibiotic use time, hospitalization time and hospitalization costs in the experimental group were better than those in the conventional group (P <0.05). Conclusion For patients with skin and soft tissue defect of the extremities, free flap repair can effectively improve the flap survival rate, promote the joint function recovery, reduce the pain degree of patients, reduce the frequency of dressing change, shorten the treatment time, and reduce treatment costs, which has positive significance for improving the treatment effect.