Taking head circumference of infants as the higher limit, numerical models of subway train getting fire in tunnel were established based on gas dynamics and combustion theory with the software FLUENT. Smoking-exhausting required time and pressure inside and outside of the train with different speed and opening door scheme was simulated, which showed that the smoke inside the railway carriage could be rapidly exhausted when the door opening degree was 0.07 m and the speed was 30 km/h. Experiment result in the Window of the world and the chiwan 2 Line of Shenzhen metro was consistent with numerical approach, which indicated numerical analysis for emergency smoke-exhausting mode was reliable with high accuracy.