Objectives The aim of this study was to compare complications and outcomes between intracranial aneurysms treated with the Pipeline embolisation device (PED) alone or with PED combined with coiling for different-sized aneurysms. Method Patients with aneurysms treated by PED were collected from the PED in China postmarket multicentre registry study. We performed a propensity match analysis to compare the efficacy and safety between PED alone and PED combined with coiling treatment, and then aneurysms were organised into three groups based on their size: small (<= 7 mm), medium (<= 15 mm to >7 mm) and large/giant (>15 mm). Complications and aneurysm occlusion rates in the aneurysm size groups were compared between PED alone and PED combined with coiling patients. Result A total of 1171 patients with 1322 aneurysms were included. All patients received clinical follow-up, while angiographic follow-up was available in 967 aneurysms. For small aneurysms, there was no difference in the aneurysm occlusion rate between two groups (79.1% vs 88.4%, respectively), while there was a significant increase in the ischaemic complication rate (8.3% vs 19.3%, respectively, p=0.0001). For medium and large/giant saccular aneurysms, PED combined with coiling significantly improved the occlusion rate (medium aneurysms: 74.7% vs 88.8%, respectively, p<0.0001; large/giant saccular aneurysms: 72.9% vs 86.9%, respectively, p=0.018), while there were no differences in the total complication rate. For large/giant non-saccular aneurysms, two groups showed no differences. Conclusion Use of the PED with adjunctive coils can significantly improve the occlusion rate of medium aneurysms, without increasing the total complication rate.