[Objective] The possible mass movement distance resulted from the instability of the abandoned dreg sites was studied for life and property security and environmental protection.[Methods] In accordance with the summarized historical data about 1 032 samples from soil accumulation, landslide mass and volcanic fluids, 882 effective data were selected by statistical analysis, and two models with regard to site selection were proposed.[Results] The corresponding safe distance for waste rock and soil accumulation in the different scales was calculated by the historical frequency. The 2.78, 5.88 and 14.29 times of its distance corresponding to the waste rock and soil accumulation were suggested for 5, 4 and 1 class abandoned dreg sites. And the 7.14 times of its distance corresponding to the waste rock and soil accumulation was suggested for 2 and 3 class abandoned dreg sites. The numerical prediction method with a highly application for loess accumulation was proposed to determine the safe distance by the theoretical modification and evaluation of the existed experience models, considering the mass scale, landform and rock classification.[Conclusion] The historical frequency method with a simple procedure can be widely used and accepted. The numerical prediction method has higher precision with iterative computation.