Background and Aims For patients with aorto-iliac aneurysm accompanied by bilateral internal iliac artery aneurysms (IIAA), iliac branch device (IBD) is the first choice for preserving unilateral internal iliac artery (IIA) at present time. However, the application of commercialized IBD is limited by the individual anatomical differences, so it difficult to meet the conditions of all patients. Therefore, this study was performed to investigate technical feasibility and safety of unilateral IIA preservation by extended application of IBD.Methods The clinical data of 3 patients with aorto-iliac aneurysm including bilateral IIAA whose unilateral IIA was preserved by extended application of G-iliac^TM IBD with different approaches during endovascular abdominal aortic aneurysm repair (EVAR) in Department of Vascular Surgery, Xiamen Branch, Zhongshan Hospital, Fudan University from April 2021 and June 2021 were retrospectively analyzed.Results All the 3 patients were males, aged from 66 to 70 years. The maximum diameter of abdominal aortic aneurysm (AAA) was 29-56 mm, and the valid and maximum diameter of lumen of the preserved IIA was 10-11 mm and 17-20 mm, respectively. The diameter of the common iliac artery (CIA) and external iliac artery (EIA) in the preserved side was 15-28 mm and 13-18 mm, and the maximum diameter of the dilated portion of the embolized IIA was 25-37 mm. In the 3 patients, EVAR was performed, and using the G-iliac^TM IBD, the side with relatively small IIAA was preserved, while the other side with relatively large IIAA was embolized. The technical success rate was 100%. The extended strategies for preserving unilateral IIA included using the bridging stents of IIA to anchor the relatively healthy lumens of its main branches, and utilizing the enlargement characteristic after post-dilation of the distal end of the balloon expandable covered stent to strengthen the sealing area between the stent and the distal end of the dilated IIA. There were no major adverse events such as myocardial infarction, cerebral infarction, massive bleeding, or death occurred during perioperative period. A type Ib endoleak from the preserved IIA occurred in one patient, which disappeared after balloon post-dilation, a type II endoleak from the inferior mesenteric artery occurred in one patient, which showed no obvious change before discharge and on 3 months after operation, and a type II endoleak from the embolized IIA occurred during follow-up in one patient, which disappeared on 3 months after operation. No symptoms of buttock claudication and stent-related complications such as stent fracture, migration, and embolization were noted in all patients during follow-up period.Conclusion For patients with aorto-iliac aneurysm accompanied by bilateral IIA aneurysmal dilation, the extended application of IBD with multiple appropriate strategies for preserving unilateral IIA device is safe and feasible during short-term period. The mid- and long-term results require further follow-up observation.