Abstract: When the elastoplastic finite element method based on the shear strength reduction (SSR) technique is employed to analyze slope stability, whether the values of elastic modulus and Poissons ratio of slope need to be reduced or not is studied in this article. It is shown that the abruptness of the displacement or deformation at a certain characteristic location and the connectedness of plastic zone are not depended on the values of elastic modulus and Poisson's ratio. In fact, stability analysis with SSR is based on the suppositional stress field or strain field got by FEM. So, it has no influence on the characteristic supposition nature of stress field or strain field with different values of elastic modulus and Poissons ratio. In consideration of? the convenience in FEM analysis, it is suggested that there is no need for reducing the values of elastic modulus and Poisson's ratio with SSR in slope stability analysis.