Abstract: Large-scale migration of hard thick magmatic rocks of overlaying rocks at working surface may induce dynamic disasters as rock burst and outburst of coal and gas.It can easily lead to sudden subsidence of the surface.Taking the first mining face of a coal mine as the background，discrete element numerical simulation on mining caving method and filling method for supper-thick magmatic rocks are carried out to analyze the effect of filling on migration of magmatic rocks and mining stress.Research shows that by the caving method，the abutment pressure at first migration of magmatic rocks increases rapidly，with the maximum peak at 45.97 MPa，which may easily induce the dynamic disasters as rock-burst.Upper rocks moves synchronously with the first migration，and the subsidence rate significantly increases with maximum subsidence of 1.21 m.By backfill mining method，the abutment pressure change less，with maximum peak at 25.88 MPa.Compared with the caving method and at the same advancement，overlying strata subsidence of magmatic rocks is only 0.044 4 m.Thus the backfill mining method can effectively reduce the stress of surrounding rock and the surface subsidence，and lower the risk of the dynamic disasters.

Key words: Magmatic rocks, Numerical simulation, Backfill mining, Dynamic disasters