The subway tunnel will be built in the plateau where the pressure is relatively low, and the tunnel will tilt at a certain angle due to topographic factors. In order to investigate the smoke transport characteristics of moving subway trains caught fire under different ambient pressures and different tunnel inclination angles, three-dimensional full-scale calculation models of subway trains, two stations and one tunnel are established, and three different environmental pressures (50kPa, 75kPa, 100kPa) and three different tunnel inclination angles (− 1.5 °, 0 °, + 1.5 °) are simulated. The IDDES turbulence model based on kω-sst RANS combined with the overset grid technology is used to simulate the subway train movement and the detailed flow field. The velocity and temperature distribution characteristics and smoke concentration field are studied in detail. The soot density of smoke and temperature increases with reduced ambient pressure due to the weakening of air entrainment and the decreased air density and the influence of ambient pressure on smoke diffusion decreases with the increase of pressure. The longitudinal airflow induced by the stack effect under the negative inclination angle of the tunnel is helpful to prevent the flowing back of smoke.