Abstract: In order to determine the impacting mechanism of coal mining on unconsolidated aquifer in the area covered by thick loess, under the geological background of Changcun Coal Mine, based on the similarity principle, physical simulation with different mining depths and heights was designed to investigate the strata failure and drawdown rate of the groundwater level of the overlying unconsolidated aquifer caused by coal mining. The results show that coal mining has different impacts on the overlying unconsolidated aquifer, which makes the aquifer affected to different degrees. Whether the fractured water-conducting zone is connected with the unconsolidated aquifer is not the only reason for unconsolidated aquifer been destroyed and the groundwater level drops, the deformation and failure of the water-barrier floor of the unconsolidated aquifer is another key factor for the failure of the unconsolidated aquifer.