Stadium vomitory width plays a very important role in the evacuation process of large number of spectators. The current estimation method of vomitory minimum width in China building codes often brings architects misunderstanding in the egress design and evacuation performance of stadiums. Therefore, this paper investigates the composition of spectator crowds in different events hosted in stadiums, their movement capability and way-finding behaviors, build a typical unit of terraced stand based on the parameters given by building codes, use agent-based model STEPS to simulate and analyze the effect of vomitory width on stadium evacuation efficiency. The simulated results show that the vomitory width affects stadium evacuation efficiency very differently. Architects should organize the circulation system reasonably and provide guidance for spectator crowds while designing the stadiums, not blindly increase the vomitory.