Abstract: To study the influence of tail roadway configuration to the gas flow field in goaf，we established the mathematical-physical model of working face and goaf with tail roadway according to the roadway layout in N1-2 Face．Combined with the influence of periodic weighting on the porosity of falling objects in goaf，we analyzed the step change of porosity according to the step of periodic weighting，and calculated the size of the segment permeability reasonably．Meanwhile，according to percolation theory of the gas flow in porous media，we compared the simulation results of three turbulence models in FLUENT to the measured results，and selected the Realizable k-ε model to simulate the air leakage field and gas concentration field under different conditions．The simulation results and field effects shows that when comparing the distribution simulation results of gas field with the measured gas concentration under the conditions of uniform penetration and sub-permeability respectively，the simulation results of sub-permeability are closer to the measured values．Influenced by the changes of gas concentration gradient and permeability in goaf，the greater the air flow distribution，the smaller the air leakage on the upper corner of tail roadway，and the smaller the step distance of tail roadway，the lower the gas concentration around the face．Comprehensively considered the amount of construction on tail roadway and the air volume distribution on air-return way，the best effect can be achieved when the step distance of tail roadway is 50 m and the air volume takes up 2/3 of the total intake airflow．Combined with the factors of step distance of tail roadway，distribution and regulation of air volume，periodic weightings，et al，a comprehensive measure has been developed to improve the utilization of the tail roadway，which has effectively solved the fluctuation and overrun situation of gas in upper corner and air-return way of fully mechanized caving face with tail roadway configuration．

Key words: tail roadway, permeability, goaf seepage, numerical simulation