Abstract: An underground two- story island subway station in Shanghai was taken as the research object, and FDS was used to numerically simulate the fire in the station area. The characteristics of smoke layer under the coupling effect of sprinkler system and smoke exhaust system in platform floor public area fire was analyzed. By analyzing the changes of temperature at height of 2.0 m, smoke layer height, visibility and velocity of smoke exhaust outlets in the fire area, the interaction between the automatic sprinkler system and the smoke exhaust system in subway station fire was discussed, and whether the automatic sprinkler system has the necessity of opening and whether the smoke exhaust system needs to be opened at the same time were confirmed. The analysis results showed that: when the pressure is low, the temperature of the smoke layer can be effectively reduced without destroying the stability of the smoke layer under the coupling effect of the automatic sprinkler system and the smoke exhaust system. As the pressure increases to a certain value, the efficiency of smoke exhaust system decreases, the stability of the smoke layer will be lost, and a large amount of smoke will accumulate in the spray area, affecting the evacuation of people near the fire. 

Key words: subway station, auto sprinkler system, smoke exhaust system, coupling effect, smoke layer