Abstract: In order to obtain the water inrush mechanism of concealed minor faults in coal seam floor during mining, the authors analyzed the evolution law of the fl oor crack and the formation law of the seepage water inrush channel regulation. The RFPA2D- Flow software was applied to analyse the dynamic process development of floor rock crack development, perforation failure, the water inrush channel formation and floor water inrush during the process of mining in the concealed faults, crack production and extending, evolution process of the formation damage area and seepage transport progress in the mining were gained. The results showed that there we re two stages during the process of concealed minor faults water bursting, the active stage and the fracture zone expanding stage. There were some differences for cra ck connection of concealed minor faults in the different location of the floor, the nearer to the mined- out area, the more potential minor faults activation formed water in rush channel, with the increasing of goaf unloading concealed minor faults the possibility of water inrush was gradually increased.