Abstract: There are hearly 150 high loess slopes(height over 30 m)cutting in highway construction in the northwest of China. As effective engineering techniques have not been developed for design high loess slopes in harmony with the geotechnical environment,60 slope failures happened due to unsuitable design and subsequent heavy rains.The purpose of this paper is to illustrate the application of a numerical finite element method for some findings common in the deformation and failure of high loess slope subjected to rainfall and earthquake conditions. According to the investigations on all failed slopes, the type of high loess slope failures is always slumping both landslide and collapse. The results for nonlinear-elastic and elatic-plastic numerical analysis of slope show that a developing pnxess of this slumping is as follows: the creep of slope body leads to the tensional cracks produced on the upper edge of slope, and to the sliding zone formed in the middle of lower slope and gradually expanded, at last to slope collapse. In addition, both the shear failure zone largely expanded by rainfall increasing and the shear stress greatly raised due to seismic force may quicken the loess slope failure.