Abstract: Finite element analyses are employed to simulate soil-reinforcement interaction, and to investigate the performances of shear zones and failure modes in reinforced soil slopes, as well as the influences of reinforcement modulus and density. The results show that the slopes with and without reinforcements differ significantly on the failure modes, and the reinforcements with different density and modulus also result in various performances of shear zones. With very low reinforcement modulus, the shear zones and failure modes in reinforced slopes approach those in soil slopes, and the stabilizing effects of the reinforcement appear insignificant even with increasing reinforcement density; With reinforcement modulus increasing, the influences of reinforcement become more significant. The widths of the shear zones increase with the increasing density and modulus of the reinforcement and tend to move into the slopes and the foundations. The results also indicate that with the soil strength and density of the reinforcement kept constant in the reinforced slopes, there exist three failure modes as the reinforcement modulus increases.