Abstract: Based on the relation between the destructive condition of coal seam floor and the change of rock strata resistivity, high-resolution electric device is used to carry out real-time measurements for the resistivity of floor rock strata in the similar simulation experiment about confined water mining. Though the change of resistivity, it can deduce the destructive condition of floor, find the water inrush point and predict the water inrush position. By comparing resistivity isopleths map before and after the mining, it obtains that its resistance change can reflect the floor crack evolution law and it is in accordance with the field observation roughly. This indicates that it is feasible to monitor the destructive condition of floor by monitoring the resistivity change of its rock strata floor.