Abstract: This paper studies the actual engineering geology and hydrogeological conditions of the dump in Nanwa village,which is the important part of Donglutian open-pit coal mine in the pingshuo mining area,an engineering geological model for slope stability study in Donglutian open-pit coal mine is established,the distribution characteristics of stress, displacement and plastic zone in slope instability are simulated by PFC software,the deformation failure mode and instability mechanism of slope were proved,then slide limit balance analysis software is used to evaluate the slope stability of nanwa village dump,finally, the prevention measures of slope deformation and failure are put forward according to the actual conditions,it provides theoretical basis for ensuring slope safety and realizing efficient production.