Popliteal cyst, deep popliteal bursa swollen or knee joint synovial back bulging, can not only result in knee swelling and pain, but also touchable elasticmass. Unlike other periarticular bursae, it features itself by the connection with the knee joint via an opening in the joint capsule posterior to the medial femoral condyle. Many scholars believe that this valve-like mechanism relates with the cysts in adults. Popliteal cyst always associates with intra-articular lesions, which can be found in children occasionlly in physical examinations. It is chronic, persistent, and also is acute while the pseudothrombophlebitis cyst rupture occurrs. The ultrasonic and magnetic diagnosis is of high accuracy. Magnetic Resonance Imaging ( MRI ) can also provide differential diagnosis reference, which is the ifrst choice in recent years. The etiology, pathogenesis, clinical manifestations, diagnosis, differential diagnosis, and the latest research progress for popliteal cyst are reviewed in this paper. This paper also discusses and makes a comparison between conservative treatment, minimally invasive operation and invasive operation.