Ankylosing spondylitis (AS) is a chronic systemic connective tissue disease of unknown origin, involving mainly the sacroiliac, hip, intervertebral and cribriform joints. There are three clinical stages i.e. early, progressive and stable. Most scholars have staged the disease according to the degree of damage to the sacroiliac joint. Meng Jiaxiao et al. classified the CT manifestations of sacroiliac arthritis in AS patients into 0 – IV with reference to the New York criteria, and considered that early stage corresponds to CT grade I-II, clinically progressive stage corresponds to CT grade III, and clinically advanced stage corresponds to CT grade IV. BASRI was reported by MacKay, Calin, etc., and then endorsed by the ASAS working group, and is a radiological scoring standard for AS that is now widely used internationally. It evaluates the cervical spine, lumbar cone, sacroiliac joint, and hip separately, and is currently the only standard that grades the hip, but not the thoracic spine, and it has a total score range of 2 to 16. Although there is some positive correlation between the severity of sacroiliac joint damage and the severity of both spine and hip damage (both P values less than 0.01), however, it is evident from the coefficient of determination of both This correlation was not significant, with the degree of sacroiliac joint damage explaining only 20.3% of the spine damage and 21.9% of the hip damage. It is clear that the severity of sacroiliac joint damage is not a good representation of the severity of spine and hip damage, and the staging of the disease by sacroiliac joint changes is not a true and comprehensive reflection of the disease. Due to the need for treatment, we have integrated the X-ray manifestations, clinical symptoms and signs, prognosis and other aspects of AS staging to be more clearly described, and added the clinical stage of fibrous ankylosis. The gradation of sacroiliac joint involvement is a necessary condition for confirming the diagnosis of AS, but in principle, it is no longer used as a reference indicator for clinical staging. There are roughly three stages: (1) insidious stage (early stage): patients with AS who do not yet have limitation of spinal or peripheral joint movement, which have not yet reached the 1984 New York criteria and are clinically difficult to diagnose, and are basically retrospective diagnoses; (2) progressive stage: patients who have reached the 1984 New York criteria and have progressed, with mild or moderate limitation of spinal and/or peripheral joint movement, and who still respond well to drug therapy; ( 3) ankylosing phase, which is divided into two stages: 1) fibrous ankylosis: severe limitation of movement of the spine and/or peripheral joints, little improvement with conventional medication, and imaging shows that the joints have not yet partially or completely fused; 2) bony ankylosis: severe limitation of movement of the joints, and imaging shows that the joints have partially or completely fused; entering this stage means that it is difficult to reverse the course of the disease with conservative treatment, however, appropriate treatment can still However, appropriate treatment can still improve functional limitations in other areas. In addition, the area to be treated should be individually graded using internationally accepted X-ray scoring criteria such as BASRI or mSASSS, as needed. For example, for patients receiving spinal orthopedic treatment, it is important to have an accurate grasp of the degree of involvement of the area that needs orthopedic treatment in order to choose the appropriate treatment plan; for example, for AS patients with limited hip movement, according to our clinical observation, the degree of joint space narrowing on X-ray does not correlate positively with the range of joint movement. In some cases, the joint gap is almost gone, but there is still some range of motion. Therefore, it is important to grade the involvement of the hip according to CT or X-ray before treatment, whether it belongs to grade IV complete bony ankylosis or fibrous ankylosis due to reversible soft tissue changes, which is very meaningful for guiding clinical treatment and analyzing the prognosis.