Abstract: In this paper the seismic stability of No. 4 tailing dam at Dexing Copper Mine is studied. Both static and dynamic response analyses have been carried out using nonlinear finite element technique. In these analyses the experimental data obtained from laboratory triaxial test of tailing meterials and two bed rock accelerographs recorded during Tangshan and Songpan earthquakes and scaled to the maximum accelerations of 200 and 400 gal respectively were used.In addition, a simplified method of evaluating the earthquake- induced pore pressure is given to predict the liquefaction potential of soil elements in the various parts of dam.