Ankylosing spondylitis (AS) is a chronic progressive disease that affects the sacroiliac joints, spinal processes, paraspinal soft tissues and peripheral joints, and may be associated with extra-articular manifestations. The cause of AS is unknown. There is a clear family history of AS. Clinical manifestations: It starts with unexplained low back pain and sacroiliac joint pain with morning stiffness, which is relieved after rest. The disease gradually progresses upward, with chest and back pain, stiffness of the thoracic and rib joints, restricted thoracic expansion and movement, and restricted and stiff spine movement. In severe cases, hunchback and bilateral knee flexion may occur. Physical examination of the sacroiliac joint is painful, the spine is stiff, and both hip joints are involved and may show a swaying gait. The earliest changes of AS occur in the sacroiliac joint. X-rays of this area show blurred subchondral bone margins, bone erosion, blurred joint spaces, increased bone density and joint fusion. The degree of lesion of sacroiliac arthritis on X-ray is usually classified into 5 grades: grade 0 is normal, grade I is suspicious, grade II has mild sacroiliac arthritis, grade III has moderate sacroiliac arthritis, and grade IV has joint fusion ankylosis. Late stage spinal bones and ligaments appear calcified with bamboo-like changes. ct or MR can assist in the diagnosis. Laboratory tests: In active patients, increased blood sedimentation, increased C~reactive protein and anemia are seen. Rheumatoid factor is negative and immunoglobulins are elevated. Treatment: In the early stage, symptomatic treatment and prevention of deformities are the mainstay, with the application of non-steroidal drugs (NSAIDS), salbutamol, glucocorticoids, methotrexate and other drugs. In patients with mid- to late-stage spinal ankylosis, stripping of the lumbar dorsalis, sacrospinous and gluteal muscles, destruction of the supraspinous and interspinous ligaments and spinal nerve return compression surgery are feasible to address local pain symptoms. For patients with ankylosis and deformity of the hip joint, total artificial hip replacement is feasible.