Objective To investigate the factors affecting the prognosis of posterior communicating artery aneurysm (PCoA) to provide theoretical foundation for treatment of PCoA.Methods The clinical data of 308 patients with PCoA,admitted to our hospital from January 1997 to June 2013,were studied retrospectively.With the therapeutic effect as the dependent variable,Logistic regression analysis was performed to examine 13 factors those potentially affected the outcomes of the patients.Results The patient's gender,side and size of PCoA,position and pointing of PCoA,timing of surgery and rupture or not during operation did not affect the outcomes of the patients (patient's age,gender,times of subarachnoid hemorrhage (SAH),Hunt-Hess grade,preoperative condition of consciousness,side and size of PCoA,position and pointing of PCoA,timing of surgery,rupture or not during operation,degrees of SAH and postoperative complications).But univariate analysis showed that the patient's age (P=0.003),times of SAH (P=0.005),Hunt-Hess grade (P=0.000),preoperative consciousness situation (P=0.003),degree of SAH (P=0.001) and postoperative complications (P=0.000) were the independent risk factors affecting the postoperative outcomes; whereas the Hunt-Hess grade and postoperative complications are fundamental risk factors that affected the postoperative effects (OR=14.330,P=0.000,95％CI:2.005-102.396; OR=19.445,P=0.004,95％CI:2.513-150.442).Conclusion Preoperative Hunt-Hess grade and postoperative complications are independent risk factors affecting the prognosis of patients; through analysis of these factors,the prognosis of patients can be broadly determined,thus the treatment of PCoA can be further guided and level of clinical treatment can be improved.