Based on the concentrated deformation and destruction characteristics of excavation damage slopes in Wenchuan earthquake，as granite the media of excavation damage slope for the finite element model. In 45° slope as the natural slope，the excavation damage effect and seismic dynamic response of different excavation angle have been studied under the excavation high is certain condition, it’s include natural slopes, excavation angle 56°, 72° and 90°. Analysis shows that excavation damage not only themselves destroyed the stress balance of slopes, but also impact on the seismic dynamic response of slopes, and the seismic dynamic stress, displacement and acceleration increased with the increase of slope angle. It’s not conducive to the stability of slope and the results coincides with the investigation conclusion that Wenchuan earthquake mountain disaster outbreak in the terrain mutation site. And the analysis also shows that slow excavation angle is an important measure to improve the seismic performance of the slope.