Abstract: With the deepening of coal mining depth, a large number of collapse columns in North China have become more and more serious in the safety of coal mining in this area. It is increasingly important to carry out research on the water inrush mechanism of concealed structural floor on confined water. In this study, the 9102 working surface was simulated by FLAC3D numerical simulation software. From the two aspects of the stress distribution characteristics of floor and the development characteristics of plastic zone, the influence of the concealed structure on the mining face under the working face is analyzed, and the safety distance of the grouting transformation of the concealed structure is obtained. Using the floor strain gauge to monitor the damage of the bottom plate after grouting and verify the grouting effect. Finally, the depth of damage of the floor containing the concealed structure caused by the mining of the working face is obtained, and which provides a reference for the safe production of the concealed structural coal seam on the pressure-bearing water floor.