Abstract: During the process of mineral exploitation, extensive unreasonable slag discharge and mine debris flow induced by high intensity rainfall can cause tremendous risks to the normal production and personnel safety. Meanwhile, massive slag heaps are distributed along the gully. The slag heap at lower elevation can be impacted by the debris flow caused by the failure of slag heap at higher elevation. Its failure probability can greatly increase. The disaster chain effect, shown with the spatial successive influence, is an important formation character of mine debris flow. The Luanshi gully is taken as study area. It is at Xiaoqinling, China. The study is based on the detailed investigation of slag heaps. The height, slope angle and volume of slag heaps, continuing heaping or not, original terrain slope and rainfall confluence cumulant are selected as indexes to evaluate the stability of slag heaps. The travel distances of mine debris flow are estimated using an empirical-statistical model(UBCDFLOW)considering width of path, slope angle and the type of flow behavior. Subsequently, the chain effect of the mine debris flow and the relative position between the slag heaps at higher and lower elevation are considered. The slag heap hazard assessment under disaster chain effect is obtained. It is concluded that the failure probabilities of slag heaps influenced by debris flow are increased distinctly. The results can provide useful advices for risk assessment and treatment design of slag heaps in Xiaoqinling Luanshi gully.