Abstract: Gas concentrations of different sections in return airway of working face were tested, and the gas distribution contours of roadway section were made for studying gas concentration distribution. Conclusions: gas distribution in different sections of roadway is uneven, and gas will be fully homogeneous with air after moving 100 m in front of working face; goaf gas pouring out through the upper corner has a greater impact on distribution of gas concentration. Recommendations for layout of gas monitoring points and sensors in return air of working face were provided, namely gas sensors in return airway should be arranged in central line of the roadway less than 300 mm away from the roof, and a sensor measuring point should be arranged at the place 10 m away from the upper corner.