Abstract: Displacing coal seam methane by gas injection was a new concept to strengthen coal seam pre-pumping, it had been tested successfully in Yangquan Mining Area. In this paper, it determined the gas injection influence radius of coal seam methane displacement by using practical measurement method in NO.15 coal seam of Shigang Coal Mine, it was found that the influence radius in bedding and vertical direction was different, and it analyzed the reason. It put forward the suggestions to arrange gas injection holes to avoid displacing the blind zone, in order that the coal seam outburst elimination can be better achieved.