FDS ( fire dynamics simulator), a field simulation software, was used to investigate the
spread regularity of smoke and its influencing factors in order to determine the reasonable relative
position of smoke tower and passageway ofa subway station to prevent the smoke extracted through the
smoke towerwhen a subway fire occurs running back into the station. The simulation results indicates
that the possibility that the smoke extracted through a smoke tower runs back into a subway station
through its passageway is related to smoke temperature, spatial distance between a smoke tower and a
passageway, and direction and strength of nature wind and so on. A field experiment shows the
availability of the simulation results.