Abstract: Lu'an Group Changcun Coal Mine is a high gassy mine. S6-7 and S6-6 working faces use the ventilation type of one intake airway and two return airways. The shared tail roadway is arranged with exterior misaligned type. The S6-7 tail roadway is affected by the adjacent face secondary dynamic pressure, so that the reasonable arranging horizon is crucial. Through numerical simulation, the paper analyzes the laws of surrounding rock pressure, strain and fail of tail roadway under secondary dynamic pressure according to different layout horizons. Taking all factors into account, the reasonable arranging horizon of S6-7 gas tail roadway should be in coal seam roof.