[Objective] To introduce the surgical technique and preliminary clinical results of posterior closed osteotomy through fracture line in ankylosing spondylitis with stress fracture. [Methods] From January 2010 to June 2021, 16 patients underwent this operation. Make a posterior midline incision. Screws were placed on either side of the pedicle. Subperiosteal dissection along bilateral spinal fractures. Exposure of the dural sac and nerve roots. Install temporary fixed rod, remove all kinds of tissue of fracture seam; If corrective kyphosis is needed, "V" shape repair is performed through fracture suture. Do the same on the opposite side. Implant bone pellets or titanium cage. Install the fixed rod, gradually close the osteotomy line, and lock the nut when the orthosis is satisfied. [Results] The mean follow-up was 25.1 months. At the last follow-up, thoracic kyphosis (TK), global kyphosis (GK), angle of the fusion levels (AFL), local kyphosis (LK), sagittal vertical axis (SVA), visual analog scale (VAS) and Oswestry disability index (ODI) were significantly improved compared with preoperative results(P<0.05). All the patients had bone fusion at the fracture end. 8 patients could not walk with eye level before surgery, and 1 patient recovered with decreased muscle strength of lower limbs after surgery and recovered after rehabilitation treatment.[Conclusion] The posterior closed osteotomy through the fracture line can completely remove the necrotic tissue of the fracture end, relieve the pain obviously, and correct the deformity at the same time, which is beneficial to fracture healing, so it is a safe and effective operation.