Objective To discuss the diagnosis and treatment of posterolateral corner injury of the knee joint, and to evaluate the clinical results after anatomical reconstruction. Methods Sixteen cases of posterolateral cornerinjury of the knee were treated, being accompanied with grade Ⅲ or above existing serious varus or external rotation. At a mean follow-up of 13 months(7 to 18 months),weevaluate the clinical results using Lysholm and IKDC(international knee documentation committee) scoring systems. Among them,there were 14 males and 2 females aging 19-46 years (mean 38 years). It was 4-12 d from injury to operation. On conditions of anesthesia, varus stresstest(VST) showed that instability of varus was more than 10° under the 30° and 0° of genuflexion respectively and external rotation test showed that instability of external rotation was more than 10° when compared with normal side. Five cases complicated by rupture of anterior cruciate ligament,8 cases by rupture of posterior cruciate ligament and 3 cases by rupture of both ligaments. Results All patients were followed 7 to 18 months and no patients had instability of the knee. The VST showed that no abnormal lateral instability was found at 0° of flexion except 3 cases at 30° with less than 5°. Cooper test showed that no rotational instability at 90° except 1 cases at 30° with less than 5°. The range of motion of the knee was from 75° to 130° of flexion(mean 118°)and from 0° to 5° of extension. Posteroperative scores were from 54 to 96 according to Lysholm scoring systems and from 46 to 94 according to IKDC scoring systems. Conclusion Although the overall incidence of posterolateral corner injury is less than that of other ligament injuries of the knee, we should pay much attention to posterolateral corner injury because of its important role in resisting posterior tibia translation,external rotation and varus of knee. This injury can result in a significant degree of disability for patients.