Abstract: [Objective] Introduce the surgical technique of modified Stoppa approach combined with iliac spine approach for periacetabular osteotomy.[Methods] Three patients with adult developmental hip dysplasia admitted to our department from 2018 to 2019 underwent surgical treatment. One case was single hip and two cases were double hip. 3D print the pelvis and hip joints before surgery, and measure the patient’s LCE angle, ACE angle, and Tonnis angle. The stoppa incision in the middle of the abdomen is first taken during the operation. Expose the rectus abdominis sheath, separate the rectus abdominis along the white line, expose the suprapubic branch and the quadrilateral along the extraperitoneal space, place the pubic bone with the guide pin, and perform the pubis and quadrilateral osteotomy. Take the iliac spine approach to expose the anterior superior iliac spine and the iliac plate, and perform osteotomy of the acetabular iliac bone in the direction of the ischial notch, and then rotate the osteotomy block, 4 cortical screws fixed. [Results] The operations of 3 patients went smoothly. Within 6 weeks postoperatively, walk with crutches under partial weight. Until 12 weeks after surgery, the patients were disengaged and walked with full weight. [Conclusion] This surgical technique can perform osteotomy of the pubic ramus, posterior acetabular column and quadrilateral under direct vision, avoiding the risk of intraoperative osteotomy penetrating the joint, and reducing the complications of lateral femoral cutaneous nerve, obturator nerve, and vascular injury. Reduce the number of fluoroscopy and shorten the operation time. The postoperative skin scar is small and the concealment is good. It is a good choice for periacetabular osteotomy to solve the bilateral hip joint lesions in one operation.