Abstract: In order to study the diffusion law of tail gas discharged from trackless rubber-tyred vehicle in confined space mainly in underground main haulageway of coal mine, and to reveal the formation mechanism of multi-phase pollutants, the similar test platform for spatial distribution law of tail gas discharged from trackless rubber-tyred vehicle was independently built. The physical simulation test on the diffusion rule of CO and SO₂ discharged from the trackless rubber-tyred vehicle driving with tail wind was carried out. The research shows that low wind and low vehicle speed tend to allow CO and SO₂ to accumulate in the rear space of the vehicle, resulting in the increase of their concentration. By increasing the wind speed of roadway and vehicle speed to both above 0.6 m/s, the tail gas dilution effect caused by the gas flow is obvious and economical. In addition, under the dual influence of the wind speed of roadway and trackless rubber-tyred vehicle speed, the tail gas concentration at nine monitoring points decreases significantly, and the concentration of tail gas at the roadway wall affected by the detour flow of the boundary layer is low and the dilution speed is slow.