This paper investigates the shearing behavior of the liner system by using the ANSYS software. The numerical model of the direct shear test is built. The shear stress nephograms of the liner system between the geomembrane and the clay in different load steps under different normal pressures indicate the locations of the maximum shear stress, and the characteristics of the interface shear stress-displacement relations. It is shown that the stress-displacement curve does not display a hardening behavior under a low normal pressure, however, with the increase of the normal pressure the hardening behavior of the stress-displacement curve becomes more evident. The shear stress at the edge is larger than that in other places in the model. The macroscopic phenomena of the direct shear test are reproduced by the numerical simulations, and it is indicated that the numerical simulations is an effective way to study the mechanism of the internal liner system.