Sacroiliac joint blurring is mostly seen in X-ray examination, and the possible causes are trauma, sacroiliac arthritis, ankylosing spondylitis, tumor and so on. 1. Trauma: due to fall with hip on the ground, fall from a high place, causing sacroiliac joint injury, after the injury, the surrounding tissue mechanization, X-ray examination can find sacroiliac joint blurring. 2. Sacroiliac arthritis: due to sedentary, excessive weight-bearing activities, chronic strain, the sacroiliac joints have aseptic inflammatory reaction, causing destruction of the joint surface, which can be manifested as blurring of the sacroiliac joints and narrowing of the joint space in X-ray examination. 3. Ankylosing spondylitis: it is a kind of chronic inflammatory reaction that occurs in the spine, which can involve the sacroiliac joint and cause fibrosis of sacroiliac joint and the surrounding connective tissues, and it can be manifested as blurring of the sacroiliac joint in the X-ray examination. 4. Tumor: such as chordoma, due to the erosion of tumor cells into the surrounding tissues, X-ray examination can also show blurring of sacroiliac joints. There are more reasons for sacroiliac joint blurring in X-ray examination, and it may also be related to bone tuberculosis and other diseases. If the symptoms continue to be unrelieved, it is recommended to consult the doctor in time to clarify the cause of the disease and carry out targeted treatment.