Abstract: With the engineering background of working face of a mine whose mining depth is more than 1,000 meters and in which fault coal pillars with different widths exist, the tectonic stress of faults and the influence of migration of coal pillars and overlying rocks of the mining working face adjacent to the fault on the impact ground pressure were analyzed, so as to study the mechanism of induction of the impact ground pressure by fault coal pillars with different widths. The study showed that the reason of the impact ground pressure was that the tectonic stress of faults and the stress of hanging overlying rocks above the coal seam exceeded the synthetical strength of fault coal pillars with different widths. By constructing the tectonic stress model of faults, the load model of hanging overlying rocks and the bearing model of fault coal pillars with different widths, the mechanical discriminant showing whether fault coal pillars with different widths could have impact was deduced, which could be used to accurately define the impact hazard area in the fault coal pillar area and provide basis for the taking of targeted measures in advance. The field practice has been made on the research achievements and the safe mining of the working face has been realized.