Objective To summarize the clinical experience of using 3D planar guide plate combined with bundle diameter technology for extracorporeal pre-fenestration in treating complex thoracoabdominal aortic diseases.Methods The clinical data of 31 patients with complex thoracoabdominal aortic diseases,who were treated with 3D planar guide plate combined with bundle diameter technology of extracorporeal pre-fenestration at the First Affiliated Hospital of Soochow University of China from January 2017 to February 2024,were retrospectively analyzed.The patients' preoperative thin-layer chest and abdominal vascular CTA data were imported into specialized software and to create a 3D planar guide plate.Under the guidance of 3D planar guide plate technology,precise extracorporeal pre-fenestration of aortic covered stent was performed,and combined with bundle diameter technology the endovascular repair of complex thoracoabdominal aortic disease was accomplished.Results Successful operation was accomplished in all patients,and two patients had failed visceral artery reconstruction surgery.The median follow-up time was 55 months,with a technical success rate of 97.6％.The postoperative follow-up blood flow patency rate was 100％,and the phase Ⅰ patency rate of branch arteries was 98％.Three patients experienced internal leakage after surgery,and none of them developed paraplegia or died during the perioperative period.Conclusion In treating complex thoracoabdominal aortic diseases,the use of 3D planar guide plate combined with bundle diameter technology of extracorporeal pre-fenestration is simple,safe and effective,with good short-term therapeutic effect,although its long-term efficacy need to be further investigated.