Objective To investigate the influencing factors of the OMNP related to intracranial aneurysm.Method This is a retrospective study which analyze the clinical data of 162 patients with intracranial aneurysm. Recording sex, age of patients and other clinical data, including have OMNPor not , the degree of OMNP, side of aneurysm, site of aneurysm,diameter of aneurysm, time from symptom onset to treatment and so on. Employing single factor and multiple factor analysis respectively to analyze the influencing factors of OMNP,secondary data adopted chi-square test and ranked data adopted non-parametric test. Using ROC curve to calculate the critical value of the diameter of intracranial aneurysm which affects OMNP. Multiple factors adopted logistic multivariate regression analysis.Results Among 162 cases of intracranial aneurysm, 40 cases (24.7%) had OMNP, including 24 cases (14.8%) of complete OMNPand 16cases(9.9%) of incomplete OMNP. The univariate analysis showed that sex,site of aneurysm and size of aneurysm were significantly different between patients with OMNP and patients without OMNP which is related to intracranial aneurysm(P＜0.05)Site of aneurysm and time from symptom onset to treatment were significantly different between patients with complete OMNP and patients with incomplete OMNP which is related to intracranial aneurysm(P＜0.05). The logistic regression analysis showed that posterior communicating aneurysms (OR=10.32，P＜0.01) and the diameter of aneurysm over 6 millieter (OR=10.2，P＜0.01) were influence factors of OMNP. There are correlations between time from symptom onset to treatment(OR=4.92，P=0.04) and the degree of OMNP. Conclusions The site and the size of intracranial aneurysm were influence factors for OMNP. There are correlations between time from symptom onset to treatment and the degree of OMNP.