Pain and discomfort behind the pelvis is considered to be the location of the sacroiliac joints. It may be the presence of ankylosing spondylitis, or it may be localized local bone tumor lesions. You can go to the hospital in time to find a doctor’s interview, the doctor combined with the examination of the initial judgment, you can improve the pelvic CT and three-dimensional reconstruction to understand the local skeletal condition. If you consider ankylosing spondylitis, you also need to improve the HLA-B27 measurement. If the pain is caused by a tumor at the back of the pelvis, surgery should be considered. If it is ankylosing spondylitis, painkillers such as meloxicam tablets can be given routinely for pain relief, and immunosuppressants such as ezetimibe can be given to control the progression of the disease as much as possible.