A typical fire scenario in Hangzhou Dongpo grand theatre was simulated with the CFD ( computational fluid dynamics) technique，in order to improve the understanding on the fire behavior in the theater audience hall and provide technical references for mechanical smoke exhaust design． The study analyzed the effect of the development of the smoke，the effect of the smoke concentration and temperature distribution on the audience evacuation， and obtained the data about the performances of the smoke exhaust with different methods． The study shows that smoke flow inside the hall develops with a process of “lift up-ceiling jet-sink down”，affected by mechanical exhaust methods． Compared with the exhaust outlets set on the center of the ceiling，the exhaust outlets set on the side walls show a better smoke exhaust performance due to their higher adaptability to variety of fire source locations． When the fire sources are under the auditorium balcony，smoke cannot be effectively discharged by the common smoke exhaust system． For the same smoke exhaust velocity and smoke outlet volume，there is an optimal combination of the single outlet area and the number of the outlets to reach the highest smoke discharge efficiency．