Ankylosing Spondylitis (AS) is a chronic progressive disease that mainly affects the sacroiliac joints, spinal prominences, paraspinal soft tissues and peripheral joints, and may be accompanied by extra-articular manifestations. The prevalence of AS has been reported differently in different countries, such as 0.13%-0.22% in the United States, 0.05%-0.2% in Japan, and 0.26% in China. Previously, the disease was thought to be more common in males, with a male to female ratio of 10.6:1; now the male to female ratio is reported to be 2:1 to 3:1, except that the onset of the disease is slower and less severe in females. The age of onset is usually between 13 and 31 years, with rare onset after 30 years of age and before 8 years of age. The cause of AS is unknown. HLA-B27 (hereafter referred to as B27) is strongly associated with the development of AS and has a clear familial tendency to develop. The rate of B27 positivity in the normal population varies greatly by race and region, e.g., 4%-13% for Caucasians in Europe, 2%-4% for Blacks in the United States, and 2%-7% in China. The positive rate of B27 in A S patients in China is 91%. The prevalence of AS in the general population is about 0.1%, and in the family line of AS patients is 4%, and in B27-positive AS patients, the prevalence of AS in their first-degree relatives is as high as 11%-25%. This strongly suggests that B27-positive individuals or those with a family history of AS are at increased risk of developing AS. Other factors such as intestinal bacteria and intestinal inflammation are also involved in the development of AS. one of the pathological signs and early manifestations of AS is sacroiliac arthritis. The typical manifestation of spinal involvement in advanced stages is a bamboo-like spine. Synovitis of peripheral joints is histologically indistinguishable from rheumatoid arthritis. Terminal tendinopathy is one of the features of the disease. Focal mesangial necrosis of the aortic root can cause annular dilatation of the aorta as well as shortening and thickening of the aortic valve cusps, resulting in aortic valve closure insufficiency. Clinical manifestations】 The onset of the disease is insidious. The most common symptom is low back pain, which can start with peripheral arthritis in atypical cases. Patients gradually develop pain and/or stiffness in the low back or sacroiliac region, waking up in the middle of the night with pain, difficulty turning over, and stiffness in the low back when rising in the morning or after sitting for a long time, but relieved after activity. Some patients feel dull pain in the buttocks or severe pain in the sacroiliac region, occasionally radiating to the periphery. The pain can be aggravated by coughing, sneezing, or sudden twisting of the back. In the early stage of the disease, the pain is mostly intermittent on one side, and after a few months, the pain is mostly bilateral and persistent. As the lesion progresses from the lumbar spine to the thoracic and cervical spine, pain, limitation of motion or spinal deformity occurs in the corresponding area. Peripheral arthropathy develops in 24-75% of AS patients at the beginning or during the course of the disease, mostly in the knee, hip, ankle and shoulder joints, with occasional involvement of the elbow and small joints of the hand and foot. Asymmetric, few-joint or single-joint arthritis and arthritis of the large joints of the lower extremities are the characteristics of peripheral arthritis in this disease. In our patients, arthritis or arthralgia of the knee and other joints, except the hip, is mostly transient and rarely or hardly causes joint destruction and disability. The hip joint is involved in 38%-66% of cases, showing localized pain, restricted movement, flexion-twisting and joint ankylosis, most of which are bilateral, and 94% of the hip symptoms start within the first 5 years after onset. The disease is more likely to occur at a younger age and in those with peripheral joint disease. The systemic manifestations of the disease are mild, with a few severe cases having fever, fatigue, wasting, anemia, or other organ involvement. Metatarsal fasciitis, Achilles tendinitis, and other areas of tendon terminal inflammation are common in this disease. 1/4 of patients develop uveitis during the course of the disease, alternating unilaterally or bilaterally, which usually resolves spontaneously and can lead to visual impairment with repeated attacks. Neurological symptoms arise from compressive spinal neuritis or sciatica, vertebral fractures or incomplete dislocations, and cauda equina syndrome, the latter of which can cause impotence, nocturnal incontinence, bladder and rectal dullness, and loss of ankle reflexes. Very few patients develop fibrosis of the upper lobe of the lung. It is sometimes accompanied by cavity formation and is considered tuberculosis, and can also be exacerbated by concurrent mycobacterial infections. Aortic valve atresia and conduction disturbances are seen in 3.5-10% of patients, and AS can be complicated by IgA nephropathy and amyloidosis.