To investigate the clinical effects of free transplantation of expanded ilioinguinal flaps in the reconstruction of severe scar contracture after extensive burns. A retrospective observational study was conducted. From August 2017 to October 2021, 7 patients with severe scar contracture deformity caused by extensive burns were hospitalized in Tongren Hospital of Wuhan University & Wuhan Third Hospital, including 5 males and 2 females, aged 26-65 years, with scar area of 20 cm×4 cm-34 cm×14 cm. In the first stage, the rectangular skin and soft tissue expander (hereinafter referred to as the expander) with rated capacity of 500-600 mL were embedded above the inguinal ligament, and then normal saline was injected after stitch removal for expansion to meet the needs of repair surgery. In the second stage, the scar was removed by surgical excision to correct the deformity and release the adhesion and contracture; after the removal of the expanders, the expanded ilioinguinal free flaps were harvested. When a larger flap was needed, the paraumbilical perforator flap was harvested at the same time, and the flaps were transplanted to the secondary wound after scar resection. The number of embedded expanders, the total amount of injected normal saline, the expansion time, the complications of skin and soft tissue expansion, the number, area, thickness, and anastomotic vascular pedicles of the expanded ilioinguinal flaps being resected, the type of flaps used, the repair method of flap donor sites, and the survival of flaps after operation were observed and recorded. The long-term repair effect and donor site condition were followed up. At the last follow-up, the patients' satisfaction with the curative effect of each surgical site was investigated according to the grade 5 score of Likert scale. A total of 10 expanders were embedded in 7 patients, of which 4 patients had 1 each and 3 patients had 2 each. The total volume of normal saline injected was 800-1 800 (1 342±385) mL, and the expansion time was 4-24 (11±5) months. One patient had the expander exposed due to infection after the expander being inserted, while the other patients had no complications of skin and soft tissue expansion. Totally 10 expanded ilioinguinal flaps with the area of 22 cm×6 cm-36 cm×16 cm ((326±132) cm) and the thickness of 0.6-1.1 (0.77±0.16) cm were harvested. Among the 10 expanded ilioinguinal flaps, 5 were pedicled with the superficial circumflex iliac artery, 3 with the superficial abdominal artery with relatively large caliber, 1 with the common trunk of the superficial circumflex iliac artery and the superficial abdominal artery, and 1 flap was anastomosed with the superficial circumflex iliac artery and bridged the superficial abdominal artery for intra-arterial supercharge. Unilateral expanded ilioinguinal flap combined with ipsilateral paraumbilical perforator flap were harvested in 4 cases, bilateral expanded ilioinguinal flaps were harvested in 1 case, and unilateral expanded ilioinguinal flap was harvested in 2 cases. Except for 1 case being transplanted with autologous split-thickness scalp to repair the flap donor site after combined resection of bilateral expanded ilioinguinal flaps, the donor sites of the other patients were sutured directly. All the flaps survived after operation without tip necrosis or wound residue. Follow-up for 3-30 (15±10) months showed that the flap was soft and not bloated, the function and appearance of the recipient area were significantly improved compared with those before operation, and the appearance of the donor sites was good. At the last follow-up, the patients' satisfaction with the treatment effect of the surgical site scored 4-5 (4.5±0.4). The expanded ilioinguinal flap can be obtained in a large area. It has the advantages of rich blood supply, less damage to the donor site, concealed location, and being convenient to be resected and transplanted in combination with the paraumbilical perforator flap. It is suitable for the clinical reconstruction and treatment of severe scar contracture deformity after extensive burns.