Abstract: The micro mechanism of the seepage in porous media such as soils and rocks is the flows in pores. The asymmetry of the pore flow causes the velocity difference called “preference flow” which is ubiquitous in seepage. The simulation of the pore flows is significant but hard for the complexity of the pores. A model for the pore flows is introduced. Firstly the PFC3D is used to generate a series of grains based on the grain composition in a cube box to simulate the soils. Then the model is cut with a plane and a representative section plane is got. With the Boolean operation, the section of the grains is subtracted from the representative section. Thus the difference of the section plane is the calculating domain of the flows. Given the boundary and initial conditions, the flows are simulated and calculated by use of the finite volume method. The velocity distribution of the pore flows is got by means of the statistical methods. The chi-squar test is used to find out the distribution function. It is found that the distribution of the pore flows obeys the gamma distribution.