Emergency evacuation under fire condition in a mass transit station is a great concern especially in developing countries. The interaction between fire and human is very important in the analysis of emergency evacuation under fire condition. An integrated fire–human model, FDS+Evac, is widely used to solve numerically the simultaneous fire and evacuation processes. However, when the simulation runs increase, the simulation time and cost will increase dramatically. The use of discrete design method (DDM) to reduce the simulation time and cost in fire emergency evacuation simulations is proposed. The method is applied to an underground subway station to study the influence of different factors on fire emergency evacuation. The grid resolution is analyzed to determine an appropriate grid size that will optimize the solution accuracy and time. Different fire locations, heat release rates, occupant loadings, ventilation conditions and material properties are considered under fire condition in the underground subway station. It shows that the heat release rate has a weak influence on fire emergency evacuation, but the fire location, occupant loading, ventilation condition and material property have a great influence on fire emergency evacuation. Furthermore, the five parameters have a coupled function on fire emergency evacuation. 
Fire emergency evacuation simulation based on integrated fire–evacuation model with discrete design method