Abstract: This paper presents a numerical simulation of quicksand or sand flow hazard through the broken rock mass in the caving zone due to coal mining based on DEM. The panel 22402 of the Halagou Coalmine was taken as the study site in this paper. The fragment-size distribution of caving zone was analyzed by using the fractal theory and then a nu- merical model of quicksand through the broken rock mass of caving zone with random shape was constructed by using DEM according to the fragment-size distribution. The simulation results show that the caving zone with large voids or pores and good connectivity are the dominant pathways for sand migration;the voids and pores in the caving zone can store the aeolian sand. The poorly graded rock mass in caving zone has a certain effect to block the sand flow;the ve- locity profiles of sand flow are of spindle type which mean that the sand flow velocities along the centerline are larger than those near the wall.