Abstract: A computational method to obtain displacement of soil slopes is presented. It is suggested how to determine the warning displacement and ultimate displacement. The main points of the method are: 1) for the local strength reduction method to obtain displacement fields of slopes under different strength reduction factors, it only reduces the strength of soils in the key region that is determinate to the slope stability, while the strength of other soils keep unchanged; 2) as a more accurate model, the variable modulus elasto-plastic model is used as constitutive model; 3) the reduced factor-displacement curve is divided into three deformation stages: the uniform deformation stage, the accelerated deformation stage and the unstable deformation stage. The displacement at the intersection point of the uniform and the accelerated deformation stages is considered to be warning displacement, and that of the accelerated and the unstable deformation stages is considered to be the ultimate displacement. Finally, the method is used in the analysis of an actual landslide. According to the reduction factor-displacement curve of the landslide, the reduction strength is very close to the strength of soils by in-situ push-shear tests, which illustrates that the proposed method is feasible to compute the displacement of soil slopes.