Objective To explore the indications, selection, and effect of flap application in repairing scar carcinoma in the lower leg and ankle. Methods A retrospective cohort study was conducted. From June 2008 to December 2018, six male patients with scar carcinoma in the lower leg and ankle were treated in Sun Yat-Sen Memorial Hospital of Sun Yat-Sen University, aged 48-64 years, with the area of lesion ranging from 3 cm×2 cm to 15 cm×6 cm. After extended resection, the defect area ranged from 8 cm×5 cm to 22 cm×9 cm, with tissue of tendon or bone exposed. Free anterolateral thigh perforator flap, latissimus dorsi myocutaneous flap, or pedicled sural neurovascular flap was selected to repair the wound according to the location of wound in the lower extremity, selection of operation position, the location of the anastomotic vessels in the recipient area, and whether there was good skin and soft tissue available in the lower leg. The size of flap was 11 cm×8 cm-26 cm×10 cm. The donor site of free flap or myocutaneous flap was closed directly by suturing in 5 cases, and the donor site of pedicled flap was repaired with full-thickness skin graft in 1 case. The blood supply and survival of flap, quality of skin graft survival, and complication were observed postoperatively. During the follow-up period, the recurrence and metastasis of scar carcinoma, and the appearance and function of donor and recipient sites were observed. Results All the patients completed the operation successfully, all the transplanted flaps survived with good blood supply, and the skin graft in one donor site survived well. The wounds in the donor and recipient sites of all the patients healed well without infection, effusion, or dehiscence, etc. All the patients were followed up for 1-5 years. No local recurrence or distant metastasis of scar carcinoma was found. The quality of the transplanted flaps was good. The shape of the recipient area was quite good, and the function of the affected limb was fine. The appearance of the donor area was good without dysfunction. Conclusions Flap transplantation is suitable for the patients with tendon and bone exposure after the excision of scar carcinoma in the lower leg and ankle. The flap can be selected according to the location of scar carcinoma, operation position, the location of anastomotic vessels in the recipient area, and whether there is good skin and soft tissue available in the lower leg. The free anterolateral thigh perforator flap or latissimus dorsi myocutaneous flap is an ideal choice for repair, which can be obtained in a large area, and the donor site can be directly sutured without affecting the function.