Posterior cruciate ligament injury (injury of posterior cruciate ligament of knee) is caused by strong violence. Posterior cruciate ligament injury accounts for 3% to 20% of all knee ligament injuries. Among them, 30% are single injuries and 70% are combined with other ligament injuries. Because among the ligament structures of the knee joint, PCL is the strongest. Biomechanical experiments have shown that the strength of PCL against external forces is equivalent to twice that of ACL. It is the main stable structure for knee flexion, extension and rotation activities, which is equivalent to the rotation axis of the knee joint. Therefore, after PCL injury, not only does it cause joint instability in the vertical direction, but it can also cause knee rotation instability. The degree of functional loss after posterior cruciate ligament injury can range from almost no impact on lifestyle to severe limitation of daily activities. Posterior cruciate ligament injury can lead to further relaxation of the secondary stabilizing factors of the knee joint, causing local pain, swelling and instability. It has been confirmed that the result of this injury in the medial and patellofemoral joint intervals is degenerative osteoarthritis. Appropriate treatment must be carried out clinically.