Objective To observe the clinical effect of microsurgical repair of Gustilo Ⅲ C floating knee injuries.Methods Ten patients with Gustilo Ⅲ C floating knee injuries were treated by operation.10 wounded limbs were classified according to Fraser classification:Ⅱ a in 3 cases,Ⅱb 2 cases,Ⅱ c 5 cases.All cases were taken the treatment of microsurgical repair combined with external fixation and fascia compartment extensive decompression.Results 8cases survived,and Phase Ⅱ amputation were procedured in 2 cases.All the patients were followed up for 6 to 36 months.There were 8 cases osseous healing,including 1 case delay union and 2 cases non-union cured by bone graft,1 case was treated with knee arthrodesis for traumatic arthritis.Tissue flap all survived with good texture,colour and lustre.5 cases had fine appearance and function.1 case had fistula form and was cured after changing medicine.Conclusion Gustilo Ⅲ C floating knee injuries can endanger the survival and function of the limbs,and the healing keys were backbone vascular reconstruction of injury limb and repair of nerve damage and soft tissue defect.Using microsurgical technique to repair and rebuild can improve the clinical efficacy.