Abstract: In order to explore the seepage characteristics of soil-rock mixture (SRM), random pore-structural models of SRM are constructed and voxelized based on the discrete element method and the proposed virtual slicing technique for three-dimensional discrete element model. Then, the three-dimensional lattice Boltzmann method is introduced to conduct a series of numerical simulations of the seepage flow in SRM from the pore scale, and the influences of rock content, rock size, relative density on the simulated permeability of SRM are comprehensively investigated. Finally, the internal mechanism of the influences of rock content on the permeability of SRM under different conditions is discussed. The results show that when the relative density and rock size both remain unchanged, the permeability of SRM presents a gradually increasing trend with the increase of rock content, and the increasing rate also increases. When other conditions remain unchanged, the permeability of SRM decreases with the increase of relative density. When the rock content is lower than a threshold value, the permeability decreases as the rock size increases, while this trend gets reversed when the rock content exceeds the threshold value. When the density of soils in SRM remains unchanged, the permeability of SRM decreases first and then increases with the increase of rock content.