Some factors affecting underground tunnel stability against earthquake are studied in this paper.The results obtained showed that the average unit weight and embedded depth of subway tunnel influencesmarkedly the post-earthquake residual deformation of subway tunnel

though has a little effect on pore wa-ter pressure. Clay content in sandy soil directly and evidently influences dynamical conduct of sandy soil inthe foundation. Finally it is explored from the point of view of energy that why inputting different earth-quake waves could result in marked distinction in dynamical reaction of subway foundation.