Taking the reinforced typical high cutting slope along Lanzhou South Ring Expressway as the research object, a three-dimensional numerical model is established for the selected typical slope by using AutoCAD and ANSYS software. On this basis, the finite differential software FLAC3D is used to evaluate the stability of the slope under the earthquake condition, so as to provide reference for the protection and safety design of loess-like high slope works. It is concluded that the slope is stable when the horizontal earthquake acceleration is 0.1g and 0.2g; the slope is basically stable when the horizontal earthquake acceleration is 0.3g; and the slope is unstable when the horizontal earthquake acceleration is 0.4g. The lattice bolt support bears large part of the tensile stress and shear strain increment, et al., with remarkable effect, and it plays an important role in slope stability. The specified seismic intensity for the highway construction region is 8 degrees with the designed seismic acceleration of 0.2g; thus, the selected lattice-supported slope is in a stable state (the stability coefficient is 1.15) under earthquake conditions, which can meet the specification.