In order to study the effect of blast shake on the stability of tunnel during mining process, finite element analysis software for rock and soil engineering is used to simulate the effect of blasting shake. In the simulation, a short-time dynamic load is applied to the rock in the blasting zone. Dynamic stress field in the rock mass and distortion in the surface of the tunnel are calculated with the method of finite element. Equivalent displacement method is utilized to determine the amount of sudden applied load, the actuation duration and the range of action. Consequently, the critical explosive dynamite amount at the critical shake speed of rock mass can be determined. This method has been used in actual engineering, and notable effect has been obtained.