Ankylosing spondylitis requires calcium supplementation, which is related to the fact that ankylosing spondylitis is often combined with osteoporosis. 1. Calcium loss and osteoporosis are common in ankylosing spondylitis. Inflammation often occurs during the course of ankylosing spondylitis, which can destroy bone and cause bone decalcification. In addition, one of the major adverse effects of glucocorticoids, which are often used in the treatment of rheumatologic diseases, is to cause osteoporosis, and poor gastrointestinal function and decreased mobility can further lead to bone decalcification. 2. The prevalence of osteoporosis combined with ankylosing spondylitis reaches 47.6%, and bone loss reaches 56.8%, and the prevalence increases with age and duration of the disease, especially the bone density of lumbar spine and femoral neck will be seriously reduced. Ankylosing spondylitis with osteoporosis will increase the risk of fracture, especially spinal compression fracture and femoral neck fracture. Therefore, calcium supplementation is necessary. 3. In the treatment of ankylosing spondylitis, it is recommended to exercise actively to enhance the body’s mobility and prevent the decalcification of bones. For patients who have already suffered from osteoporosis, it is recommended to carry out treatment and calcium supplementation under the professional guidance of doctors. Calcium supplementation for ankylosing spondylitis has its own special requirements, and the calcium supplementation program should be formulated under the guidance of doctors.