Abstract: Taking N2S3 working face of Daping Mine as the object of analog simulation, we use simulation test to study the activation and instability of reverse fault during footwall mining, and analyze the stress evolution characteristics of fault plane during the advancing of working face, and explore the influence of fault on water-inrush from working face. The research indicates that the whole evolution law of fault presents “activation of upper end, closure of upper end, activation of lower end” with the advancing of working face; the relative movement of the hanging and foot wall gradually develops to lower end. The whole activation of fault zone will cause water-inrush in mined-out area when the footwall working face is near reverse fault within the scope of 30 m. At this time, it is necessary to set up water-preventing coal pillar in the fault to achieve the purpose of safe mining.