Computational fluid dynamics (CFD) was used to numerically investigate the blood flow in 3-D models of human preoperative and posteroperative of cerebral aneurysm clip, and the feasibility of surgical operation was evaluated by the calculated hemodynamics parameters. Mimics software was used to reconstruct the models from CT angiograms, and numerical simulation of blood flow at different time in a cardiac circle was performed. Comparison analysis of blood flow in three models of human preoperative and posteroperative of cerebral aneurysm clip was conducted in terms of blood velocity distribution, wall shear stress (WSS) distribution and pressure distribution. The results demonstrated that blood velocity and WSS were significantly increased, and pressure was obviously decreased.