Objective To evaluate the value of sacroiliac joint scanning in the treatment of early ankylosing spondylitis. Methods A total of 120 patients with suspected sacroiliitis were analyzed using oblique transverse and oblique coronal thin-layer scans. Results A total of 70 cases of bilateral sacroiliac arthritis, 45 cases of unilateral sacroiliac arthritis and 5 cases of sacroiliac joint showed no significant changes. Among 70 cases of bilateral sacroiliac arthritis, 50 cases of bilateral sacroiliac joint space narrowed in varying degrees, articular surface rough and blurred, articular cartilage edema obvious, irregular interruption, thickening, flaky abnormal signal shadow in subarticular bone, part of the inflammation involved iliac bone. There were 15 cases of bilateral sacroiliac joint subchondral bone sclerosis, subchondral bone plate boundary unclear, 5 cases of bilateral sacroiliac arthritis involving bilateral ischia, bilateral acetabulum, articular cartilage surface obvious blurred, bone marrow edema. Among 45 cases of unilateral sacroiliac arthritis, 40 cases showed linear hyperintensity in the space between unilateral sacroiliac joints, abnormal hyperintensity in the rough articular surface and subarticular bone of the affected side, and 5 cases of unilateral sacroiliac arthritis complicated with involvement of internal and external iliac muscles with abscess formation. Conclusion The scanning technique of oblique cross-section and oblique coronal plane has important significance for the diagnosis of early ankylosing spondylitis and is worthy of clinical promotion.