Objective: To investigate the causes for difficulties in withdrawal of delivery system during endovascular aneurysm repair (EVAR) of abdominal aortic aneurysm (AAA) and solutions. Methods: The clinical data of 305 AAA patients undergoing EVAR from January 2008 to April 2016 were retrospectively analyzed. The causes for occurrence of the difficulties during delivery system withdrawal and corresponding solving strategies were analyzed. Results: Among the 305 patients, difficulties of delivery system withdrawal occurred in 21cases (6.89%), of whom, 18 cases were complex AAA and 3 cases were non-complex AAA; 17 cases were repaired with bifurcated stent grafts and 4 cases with unibody bifurcated stent grafts, and both differences had statistical significance (85.7% vs. 14.3%; 81.0% vs. 19.0%, both P<0.05). All the 18 patients with complex AAA who encountered difficulties of delivery system withdrawal had severe aneurysmal neck angulation, of whom, 7 cases had more than 2 successive aneurysmal neck angulations and 2 cases had concomitant short aneurysmal neck. Among patients with aneurysmal neck angulations, those with more than 2 successive aneurysmal neck angulations had the highest incidence of difficulties of delivery system withdrawal (P<0.05). All withdrawal difficulties were successfully resolved by comprehensive application of corresponding countermeasures. Conclusion: Difficulties in withdrawal of the delivery system are not uncommon during EVAR for complex AAA, especially for those with multiple aneurysmal neck angulations. However, the difficulties can be effectively resolved by comprehensive application of corresponding countermeasures.