Abstract: Based on the open-pit and underground mining engineering practice in Pingshuo mining area,the physical simulation and numerical analysis were combined to investigate the deformation-failure characteristics and stress distri- bution rule of mining slope. Therefore,the deformation-failure mode and the typical instability mechanism of mining slope under the coupling effects of key hard strata and key weak strata were revealed. A four-stages theory of deforma- tion and destruction of mining slope was put forward,including epigenetic recreation of rockmass structures stage, structure transformation stage,time-dependent deformation stage and eventually unstable (stable) stage. Then the en- gineering mechanics model was established. The criterion of mining slope into the time-dependent deformation stage and eventually unstable (stable) stage were deduced.