Abstract: As a man-made geological disaster，the debris flow in the waste dump is formed by the com‐ bined action of material source，topography and water source conditions. It has the characteristics of strong concealment，easy start-up and high frequency. Through on-site investigation，the dumping materials of a waste dump are mainly waste soil and gravel. The physical and mechanical properties of the loose accumula‐ tion body are poor，and the upper part of the fine particle content is significantly different，showing a natural grading phenomenon. In terms of topography and geomorphology，the quantitative score of the susceptibility of gully debris flow in the waste dump site is 55 points，which is a mild susceptibility level. The overall ter‐ rain is gentle and the loose material reserves are moderate. In terms of water source conditions，the average annual precipitation in the region is 656 mm，concentrated in July-September，and the maximum daily pre‐ cipitation is 109.2 mm. The drainage facilities can resist the once-in-a-century rainstorm. Based on the analysis of the current situation，the possibility of gravity，hydrodynamic and composite debris flow in the waste dump is low. Under extreme conditions ( interception and drainage failure + continuous rainstorm + six-level earthquake )，the dump may be unstable，and the debris flow scale prediction is about 6 000 m3 . The research results provide a theoretical basis for the prevention and control of mine dump disasters.

Key words: waste dump, debris flow, scale prediction