One of the internal reasons resulting in hemolysis and thrombi is the hemodynamics. Many studies show that irregular flow patterns and shear stress result in the damage of blood cells. With the rapid development of computer technology, simulation for such microdynamics becomes possible. Computational fluid dynamics was applied to predict the flow in the streamlined blood pump and a pump with straight vanes. After the analysis of flow patterns and the distribution of shear stress, it was concluded that in the same boundary conditions, the blood pump based on streamlined design had better hemodynamics than the pump with straight vanes and caused less