Objective: To investigate the effectiveness of free-style perforator flap in repairing the soft tissue defect of knee., Methods: Between December 2011 and October 2017, 13 patients with the soft tissue defects of knees were repaired with the free-style perforator flaps. There were 9 males and 4 females, with an average age of 40 years (range, 14-65 years). The injuries were caused by traffic accident in 7 cases, crushing in 4 cases, and falling from height in 2 cases. The soft tissue defects in 9 cases formed after 2 weeks-2 months (mean, 1 month) of lower extremity fractures fixation. The other 4 cases were urgently admitted to the hospital after injury, and the time from injury to admission was 0.5-18.0 hours (mean, 8 hours). The size of soft tissue defect ranged from 3 cm×2 cm to 12 cm×8 cm after debridement. Nine propeller flaps, 6 rotating flaps, and 2 V-Y advanced flaps were used; and 9 cases were repaired by single flap and 4 cases were repaired by combined flaps. The size of flap ranged from 7.5 cm×2.5 cm to 20.0 cm×6.0 cm. The donor sites were sutured directly., Results: The flaps survived smoothly and incisions healed by first intention in 12 cases. The congestion occurred in 1 case, which obtained delayed healing after symptomatic treatment. All incisions at donor sites healed by first intention. All patients were followed up 3-24 months with an average of 6 months. The shape and motions of knee were satisfactory., Conclusion: The free-style perforator flap can maximize the utilization of the donor area around the knee wound, with reliable blood supply, small trauma, and easy operation. It is an ideal flap for the soft tissue defect of knee.