Abstract: FDS( Fire Dynamics Simulator) is used to simulate the fire temperature field characteristics and smoke flow of the rectangular plan air-supported membrane structure which has abroad application in public buildings and plants． That provides the basis for the further study on performances of structural safety and safety evacuation． According to the temperature field results，the temperature indoors as well as on the membrane surface can be reduced effectively when the evacuation door and the fan are open． Moreover the structure does not collapse easily． Air vent position has some influence on membrane surface temperature． The results of smoke flow show that smoke layer declines unevenly and the laminar characteristic is not obvious in vertical plane when the vent is opened． Besides， indoor visibility reduces rapidly． Air vent position has great impact on the horizontal smoke flow where is near to the fan and fire source．