The issue of slope stability in earthquakes has become increasingly prominent with the construction of many infrastructure projects such as highways, bridges, and tunnels. To explore the dynamic response characteristics of bedding rock slopes in an earthquake, the three-dimensional dynamic finite-difference method (TDD-FDM) in this study is used to establish simplified rock slope models, taking a bedding rock slope with alternatively distributed soft and hard rock layers in Yunnan, China as a prototype. The dynamic response mechanism of layered rock slopes containing different thicknesses, locations, and quantities of soft rock layers was studied under different excitation directions of seismic waves. The main findings are that the propagation of seismic waves at different rock layer structures has directionality, which causes the strongest seismic response to be all located in the upper or middle parts of the slope; the influence of rock structures on seismic response in layered rock slopes is in the order of thickness > quantity > location; the acceleration amplification effect of a slope under multi-directional seismic wave excitation exhibits the phenomena of differential amplification and coupling amplification; and the acceleration amplification factors of a slope with increasing peak ground acceleration from 0.05 g to 0.20 g show two trends: increasing–decreasing and continuous increasing. The findings of this study can be a reference for studying the dynamic response of rock slopes in strong earthquakes.