Abstract: In order to solve the thin aquifuge floor failure depth question at 9^# coal seam of lower coal group in Dongpang Coal Mine,taking 9103 fully mechanized caving face as the engineering geological background,the theoretical calculations and empirical formula analysis method are used to determine the maximum depth of the floor failure theory value,while the numerical simulation software FLAC^3D is taken to analyze the depth of floor failure stress distribution and implementation in the field of embedded sensors and monitoring borehole stress,measuring mining stress evolution in the floor,and its floor failure depth monitoring results coincide with theoretical calculation and simulation results,which proves the feasibility and reasonableness to use various means to study of floor failure depth.