Abstract: Three gas extraction drilling holes of different angles with coal seam bedding direction were arrangemented in Xin'an Coal Mine of Yima Coal Group, the gas drainage concentration, gas flow and total pure drainage volume were investigated to uncover the gas seepage laws of drill holes under different pressure-bearing conditions in the process of working face advancing. Numerical model was set up to simulate the gas permeability of three extraction boreholes respectively, the simulation results are relatively similar with field investigation. The results show that the best gas extraction area is from 7 m to 11 m before the working face, the arrangement of boreholes parallel to the bedding of coal seam could make the gas drainage work best, the reasonable area for gas extraction equipment dismantling is 4 m to 6 m before the working face.