Abstract: The failure of mining floor is the key factor to conduct confined aquifer and induce floor wa⁃ ter inrush. In order to analyze the stress distribution of ultra-wide working face and reveal the failure mecha⁃ nism of floor strata，the 21609 working face in Binhu Coal Mine is taken as the research object，and the fail⁃ ure law of working face before and after roof cutting and pressure relief is analyzed by using mine pressure theory and numerical simulation. The results show that the working face tension mining will cause repetitive disturbance to the floor strata，and stress concentration occurs at the end of the rear working face. After roof cutting and pressure relief，the plastic zone range，vertical stress，maximum principal stress，maximum shear stress，pore water pressure and displacement of coal seam floor are significantly lower than those be⁃ fore roof cutting and pressure relief，and the concentration effect of mine pressure is weakened，which effec⁃ tively reduces the failure depth of floor，and is of great significance to the prevention and control of floor wa⁃ ter damage in super wide working face mining on confined aquifer.

Key words: ultra-wide working face, double-unit mining, cutting roof and pressure relief, floor failure