Objective: To analyze the morphological type and clinical factors that affect the prognosis of aneurysms at bifurcation of middle cerebral artery, and to provide certain scientific basis for predicting the prognosis of patients with aneurysms in clinical practice and making diagnosis and treatment plans. Methods: Patients with aneurysm in the bifurcation of the middle cerebral artery, hospitalized in the Affiliated Hospital of Xuzhou Medical University, were analyzed retrospectively, and according to the CT angiography(CTA), digital subtraction angiography(DSA) as a diagnostic basis, such as the examination to dissection aneurysm form for credit, analysis four types prognosis have differences, collect and analysis the clinical factors that may affect the prognosis of patients. Results: Type I 31(33.3%) cases, type II 19 cases(20.4%), type III 30 cases(32.3%), type IV 13 cases(14.0%). Prognosis was no difference among the 4 types(χ~2=7.603, P=0.055). Postoperative complications in patients with the four types of aneurysms were analyzed, and postoperative infarction rates of the type IV aneurysms were higher than that of the other 3 types(P=0.034), the difference was statistically significant. Clinical factors including gender, age, history of hypertension, preoperative Hunt-Hess grade, aneurysm size and postoperative complications were collected, and it was found that age(χ~2=18.422, P<0.001), history of hypertension(χ~2=4.232, P=0.036), postoperative infarction(χ~2=25.522, P<0.001) and preoperative Hunt-Hess grade(χ~2=12.319, P=0.001) had an effect on the prognosis of patients. Multivariate analysis showed that postoperative infarction(OR=0.184, P=0.022), age(OR=1.010, P=0.022), and preoperative Hunt-Hess grade(OR=2.683, P=0.025) were independent risk factors for middle cerebral artery bifurcation aneurysms. Conclusion: Postoperative infarction, preoperative Hunt-Hess grade and age are independent risk factors for the prognosis of middle cerebral artery bifurcation aneurysms. Postoperative infarction rates of type IV middle cerebral artery bifurcation aneurysm was higher than that of the other 3 types.