Abstract: Based on eastern slope constructing dump at an open-pit mine in Xinjiang Uygur Autonomous Region,using the orthogonal method to establish an experiment program,this paper performed a basal contact friction experiment to simulate slope failure,and the experiment of four typical production model fully reflected the failure process of compos-ite slope. Experiments show the 21st coal floor is the key factor of slope failure. By analyzing the displacement of moni-toring point,there are four kinds of potential sliding surface including line,straight line,broken line and circular arcs and two kinds of failure classified into subsidence and creep-crack. The paper discusses the effect of weak layer,time and dump on slope,points out the improvement for basal contact friction experiment,and proposes a reasonable rein-forcement time for stability and the importance of reasonable making model. Overlying dump have dual influences on slope stability,which controls the scale of potential sliding mass together with weak layer. The research can be applied to the prevention of multi-seam and soft rock slope in open pits.