Objective To reconstruct three-dimensional vascular model bases on CT images, and to study the influence patters of external uniform magnetic field on hemodynamic behavior. Methods The mathematical model of blood flow with external uniform magnetic field was established by using the theory of computational fluid dynamics and the method of magnetohydrodynamics. The simulation was carried out by using the multi-physical field coupling simulation software COMSOL Multiphysics to explore the effects of magnetic field intensity on blood flow velocity, pressure and shear stress. Results The magnetic field significantly suppressed the velocity at the center of blood vessel with magnetic field intensity increasing. The wall pressure decreased with magnetic field intensity increasing, and the influence of magnetic field on wall pressure before blood flow bifurcation was obvious, but the influence on wall pressure after blood flow bifurcation was weak. After blood flow entered the branch vessel,the wall shear stress increased significantly, and the effect of magnetic field on shear stress also increased significantly. Conclusions Human blood has magnetohydrodynamic characteristics, and the magnetic field in a certain intensity range has a significant impact on blood flow. The results provide a theoretical basis for the design of artificial equipment with high intensity magnetic field, evaluation for the effects of artificial magnetic field on human hemodynamics, and diagnosis of the diseases caused by artificial magnetic field.