The selection of seismic wave, meshing of finite element, input methods of wave load are of a great influence on the accuracy in simulating the earthquake response by time history method. The method of oblique incidence of seismic wave in space which is suitable for seismic analysis of underground cavern is put forward by considering the direction, multifaceted and the consistency of the seismic wave incident. The selection of seismic load and FEM principle are discussed. The solution precision is higher by comparing with the classic examples.