Background and Aims With the advancement of endovascular techniques, the safety and effectiveness of total endovascular treatment for abdominal aortic diseases have been widely validated. However, in thoracoabdominal aortic diseases, the anatomical conditions are more complex, making endovascular treatment challenging, and its safety and effectiveness require further determination. This study was performed to summarize the single-center experience of the authors' team in using fenestration/branched stent-graft for the treatment of dilatation of the thoracoabdominal aorta and introduce the team's innovative double-trunk technique for complex thoracoabdominal aortic diseases, aiming to provide reference and insights for fellow professionals.Methods The data of 37 patients with dilatation of the thoracoabdominal aorta who underwent fenestration/branched stent-graft treatment and had at least two reconstructed branch arteries from October 2021 to July 2023 in the Shanghai General Hospital were retrospectively collected. Among the 37 patients, there were 20 cases of distal aneurysmal dilatation after dissection and 17 cases of thoracoabdominal aortic aneurysms. After comprehensive preoperative CTA and evaluation, single-trunk endovascular treatment was performed in 26 cases, and double-trunk technique was used in 11 cases. Relevant clinical data (baseline information, preoperative anatomical parameters, perioperative indicators, and follow-up outcome variables) were collected to analyze the overall treatment effects and the safety and efficacy of the double-trunk technique.Results A total of 162 branch arteries were reconstructed successfully with a technique success rate of 100%. During the perioperative period, there were 3 deaths (8.11%), 3 cases of graft implantation syndrome (8.11%), and 1 case of type Ⅲ endoleak (2.70%). The median follow-up time was 13.73 (2.33-26.74) months, and the overall survival rate was 91.9% (34/37). During the follow-up period, type Ⅲ endoleak occurred in 2 cases (5.41%), stent restenosis or occlusion occurred in 3 cases of (8.11%), and dissection progression occurred in 1 case (2.70%); 5 patients (13.51%) underwent re-intervention. There were significant differences between the single-trunk group and the double-trunk group in terms of reconstruction methods, the ratio of 4-branch reconstruction, and the average number of stents used (all P<0.05), while other indicators showed no statistically significant differences between the two groups (all P>0.05).Conclusion Fenestration/branched stenting for dilatation of the thoracoabdominal aorta is a safe and effective strategy. For anatomically complex lesions where traditional single-trunk combined with fenestration/branched stent-graft is difficult to reconstruct all branches, the double-trunk technique is a feasible choice. However, the results of this study still need more cases and longer follow-up time for validation.