A tunnel model is established and the concentration of gases at the working face of tunnels is simulated on basis of conservation equation, turbulence kinetic energy equation, constituent transportation equation and standard kε model, so as to study the layout of methane sensors at the working face of tunnels with high gas concentration. The study results show that: 1) The position of air duct and the ventilation volume have great influence on the distribution of methane; 2) Under normal ventilation condition, the methane concentration at the side wall on the side opposite to the air duct is high; when the ventilation volume is insufficient, the methane concentration at the tunnel crown is high. The installation positions and amount of methane sensors are determined and rational methane sensor layout requirements are proposed.