Abstract: In order to explore the changing laws of reverse fault activating scope, based on the way of FLAC^3D numerical simulation, the analysis model of activation range was established. The range of activating reverse fault was analyzed with the relative displacement and the ratio of normal stress and tangential stress in reverse fault. The range were impacted by the mining depth, mining height, fault dip and fault properties. The activation range of fault is increased with the increase of mining depth, mining height and fault dip.