According to the gravitational deformation of slate slope in the field, this study explored the influencing factors, including the slope angle, the foliation angle, and the material deterioration on the deformation characteristics. To simulate these phenomena, a series of physical model experiments with simplified environmental conditions were performed in the laboratory. Then, the discrete element software, PFC3D was used for simulations to further our understanding of deformation behavior in slate slopes under the long-term influence of gravity and material deterioration. According to the physical model tests and numerical simulations the results possesses the following characteristics:(1) Based on the model tests, two kinds of gravitational deformation of slate slope are identified, the first one is overturning destruction, it appears in the obsequent slope with high angle foliation. The other one is fold extrusion near the slope toe, it exhibits in the consequent slope with low angle foliations. It is not only influenced by gravitation but also by wet deterioration. (2) The results of physical model test provide the basic case for the verification of discrete element simulation. The simulated deformed patterns agree well with the actual deformation under different slope angles. Therefore, the model of discrete element method and associated parameters are verified, and they could be used for the subsequent analysis in the future.