Abstract： Objective To explore the diagnosis and microsurgical treatment of "low-lying" internal carotid-posterior communicating aneurysms.Methods The clinical data of 16 cases confirmed as "low -lying" internal carotid -posterior communicating aneurysms in our hospital since 2006 were retrospectively analyzed.Epidural anterior clinoidectomy was used in 5 cases, simple incision of anterior petroclinoid fold in 8 cases and combination of intradual anterior clinoidectomy in 3 cases.Results All the patients got aneurysm neck clipping totally.There were intra -operative hemorrhage in 2 cases, transient physical activity obstacles in 2 patients and decline eyesight in 1 case postoperative.All patients got good recovery at discharge.There was no death.Conclusion We should carefully read the image data to understand the relationship between aneurysm neck and anterior clinoid preoperatively.The application of incision of anterior petroclinoid fold and/or anterior clinoidectomy are helpful for temporary occlusion of parent artery and increasing the visualization of the proximal neck of aneurysms, which could achieve good results.