Abstract: To guarantee the drilling construction safety of floor and enhance the effect of relieved gas drainage in protected seam, based on the status of drilling construction and gas drainage of that the protective layer is in serious outburst danger during the mining process of the upper protective layer, taking Qidong Mine protective layer mining as an example, by using the rock pressure and elastic mechanics theory and combined with FLAC^3D numerical simulation software, the reasonable drilling hole protected seam position and construction time are studied during the upper protective mining. The results show that the most reasonable and safety position of drilling hole in coal seam of protected No.9 coal is at the place that the delay plane distance is from the protected coal 16 to 26 m.