Abstract: In order to provide reference and basis for the escape of underground personnel in the event of electromechanical chamber fire, the fire dynamics simulation software PyroSim was used to simulate the electromechanical chamber fire occur in Xinlong Coal Mine. The gas temperature, toxicity, smoke concentration, visibility in the roadway are anlyzed. Simulation results showed that the temperature at the fire source kept rising after the electromechanical chamber fire, tended to stabilize after 250 s, reached about 550 ℃; the high-temperature smoke layer dropped to 1.6 m in 230 seconds which greatly influenced the sight of staffs. After 300 s, the visibility in the tunnel decreased to 1 meter, the escape of underground personnel became more difficult. After 400 s, the temperature of flue gas in the roadway reached to 80 ℃, which seriously affected the escape of people. The concentration of CO in the roadway did not exceed critical value, and it had no effect on people.