Two-dimensional images of the granular ore media with different grain sizes were obtained from the X-ray computed tomography. Combined with the digital image processing and finite element techniques, the original grayscale images were transformed into the finite element models directly. By using these models, the simulations of pore scale fluid flow among particles were conducted with the COMSOL Multiphysics, and the distribution characteristics of fluid flow velocity and pressure were analyzed. The simulation results show that there exist obvious preferential flow and leaching blind zone in each granular medium.The flow velocity at pore throat is larger than that of pore body and the largest velocity reaches 0.22 m/s. The velocity decreases gradually from the center of pore throat and body to the surface of particles. The flow paths of granular media with larger grain size distribute equally, while the fluid flow velocities in most of areas of granular media with smaller grain size are lower, and some of them approach to zero, so the permeability is very low. There exist some pore clusters with different pressures, which is the basic reason for the uneven flow velocity distribution.