The posterior oblique ligament injury can cause serious joint dysfunction, resulting in the instability and the degeneration of cartilage. Due to the lack of systematic understanding of the posterior oblique ligament of the knee, the clinical treatment is not effective. Domestic and international literature about knee posterior oblique ligament in recent years was reviewed extensively, at the same time, the anatomy and biomechanics function, classification of injury, treatments of the posterior oblique ligament were analyzed, and the relavent contents were summarized, and this article reviewed the research advances in the knee posterior oblique ligament, to provide theoretical basis for clinical treatment.