Abstract: Water inrushes through fault mostly produced by deformation and water conduction of the fault due to excavation, in which no water exists in initial geological condition. By means of numerical simulation and case analysis, the mechanism of deformation and water conduction of fault due to excavation has been studied in this paper. It is found that deformation and water conduction of fault due to excavation show obvious timespace effect, which is very helpful to underground engineering design, construction organization and field exploration and monitoring. 