For tunnels built in silty sand, the tunnel leakage can carry the fine particles into tunnels and generate seepage erosion, which will result in the tunnel settlement and damage the tunnel serviceability. This paper presents the tunnel displacement, soil stress distribution and ground settlement due to seepage erosion by using the discrete element method(DEM) simulation. The results show that the tunnel displacement and ground settlement increase linearly with the particles loss ratio. Particle arch formed around the erosion seam will redistribute the soil pressure; and it can lead to further expansion of the erosion seam and accelerate the seepage erosion process. And the seepage erosion in the inverse of the tunnel is more risky to tunnel serviceability than that in the tunnel waist and crown.