Abstract: This paper uses the 5 12 Wenchuan earthquake as the background. It attempts to clarify scientifically and rationally the genetic mechanism of ruptures in the soil slope(including the overlay slope)under the dynamic loading of the earthquake. The aspect is examined systematically through vibration machine simulation test which belongs to the physical simulation method.The test results show the deformation and failure under the loading of earthquake have a certain correlation with the slope external structure.Stress mainly concentrated in the slope-shape turning zones,where damage can be made easily.The instability and failure Under the condition of vibration,soil slope show an general instability and failure mode that the slope collapses completely and results its debris piled at the slope toe area. Although this study reveals some regularities, the question about the dynamic response of soil slopes still needs further study.