On basis of calculation of dynamics mountain tunnels by finite element method, the authors summarize several characteristics of seismic response of mountaincrossing tunnels in this paper. The dynamic responses of deepburied tunnels are smaller than those of shallowburied tunnels; The dynamic responses of high pressure side are stronger than those of the normal pressure side in case of tunnels with obvious unsymmetrical pressure at tunnel portals and the maximum dynamic responses occur at the hance; The dynamic responses of high pressure side are a bit stronger than those of the normal pressure side in case of tunnel with unobvious unsymmetrical pressure at tunnel portals and the maximum dynamic responses occur at the vault. In addition, the elastic modulus of surrounding rock has obvious influence on the dynamic effect of tunnels.