Abstract: Clarifying the spatial failure characteristics of mining gently inclined floor is a key problem for safe mining above confined aquifer. The current research focuses on the failure depth of mining floor, whose failure spatial characteristics are easy to be ignored. Therefore, with the 061405 coalface of Lingxin Coal Mine as the engineering background, the stress distribution and failure characteristics of mining gently inclined floor was investigated using the elastic mechanics theory and numerical simulation, and then a risk assessment method with spatial failure characteristics for floor water inrush was proposed. The research results show that: the maximum failure depth of the mining inclined floor is 21.5 m. And the failure pattern along the inclination direction of coalface presents a "inverted saddle" shape, which has the characteristics of "small failure depth near the upper side of the goaf, and large failure depth at the lower side". The overall space depth characteristics of mining gently inclined floor show an asymmetric trend with fault-like growth from the central area to the goaf surrounding of the coalface. The risk assessment result of water inrush based on the comprehensive consideration of the spatial characteristics of floor failure are consistent with the mining practice.