Abstract: The dynamic response of a large underground opening complex under seismic loads was simulated by use of the softwore FLAC3D.Two different time-dependent acceleration curves were selected as the input seismic loads and the dynamic calculations were carried out respectively.The position and extent of splitting damage zones were predicted using the new splitting criteria.The distributions of stress field,displacement field and elastic energy in the surrounding rock mass were analyzed when the seismic loads were applied.It was shown that FLAC3D could be used to simulate the dynamic response of large underground opening complex under seismic loads effectively.The influence of seismic loads on the stability of the rock mass should be considered prudently in engineering.