The safety of on-fire trains moving in subway tunnel is important to emergency rescue, and the train velocity is the key to the train safety. This paper adopts a fire prototype with a heat release rate of 0 - 10 MW to perform a model experiment of train fire in a 1 ： 8 subway tunnel model. After a similar transformation, the heat release rate of the model fire reaches 0 - 55 kW. By using n-heptane as the fuel and by adopting a frequency conversion fan to form a flow field, the motion of the train in the model tunnel is simulated, and the relationship between the wind velocity and the heat release rate, the temperature field around the train and the flame/smoke pervasion rule are in- vestigated in the conditions of variable train velocity, fire location and fire source location. Finally, by taking Beijing