A new model for seepage failure has been established in this study. Seepage field, particle concentration field, stress field and interactions among them are simultaneously taken into consideration in this fluid-soil coupling system. A hybrid numerical algorithm incorporating FEM and FVM is proposed and implemented to solve the physical equations. The numerical model is validated by successful simulation of the flow pump test experiments. Finally, soil erosion and differential settlement of a typical levee due to seepage failure in a double-layer levee foundation are simulated andanalyzed.