Abstract: In order to study the water inrush catastrophic law of the coal mine floor with concealed small fault under the influence of mining, the 16001 working face of Zhaogu No.1 Coal Mine is taken as the background, and the changes in the permeability coefficient and porosity of the rock mass with the volumetric strain are considered, and the shear stress of the surrounding rock during the mining process is considered. On this basis, the influence of concealed fault water conductivity and water pressure on the law of water inrush catastrophe of working face is studied. The research results show that the water inrush from the concealed small fault has a large hysteresis and suddenness in the working face. Only when the working face exceeds the concealed small fault by 24 m, the shear fissure zone of the working face floor can connect with the concealed small fault to form a water-conducting fissure channel, the floor water inflow of the working face can be directly jumped from 2.9 m3/h to 46.6 m3/h. When the water conductivity of the concealed small fault is poor, the shear yield zone of the floor surrounding rock under mining will not develop to the top of the fault and will not induce concealed faults to activate water inrush; the higher the hydraulic pressure of the concealed fault, the larger the scale of the working face floor shear yield zone extending toward the concealed fault. When the critical value is reached, the two will penetrate to form a water-conducting fissure channel.