Abstract: The floor failure depth after mining is an important research topic in the mining under safe water pressure of aquifer. In order to study the floor failure depth of large mining height and super-long working face, this paper selects No. 3 coal mining face in Sihe Mine as the research object, and the main factors affecting the floor failure depth are three factors: width, height and depth. FLAC^3D numerical simulation software is used to analyze the influence of three main factors on the floor failure depth. Based on the theory of multivariate nonlinear regression analysis, the prediction model of floor failure depth for mining height, depth and width is established. The results show that the influence of the three main factors on the floor failure depth is nonlinear, the order of influence is width>depth>height.