Reasonable evacuation strategies are important in reducing casualties in the event of a fire. In this work, we conduct a simulation of a fire evacuation of a large public building based on the building information modeling technology to find the best evacuation strategy. We identify the tolerance limit of evacuees in case of a fire as the basis of the simulation using the fire dynamics simulator software. The following four evacuation strategies are proposed and simulated: stratified evacuation only by stairs, stratified evacuation mainly by stairs and supplemented by fire elevators, holistic evacuation only by stairs, and holistic evacuation mainly by stairs and supplemented by fire elevators. The case study of a college canteen shows that if 10% of evacuees (mainly elderly people who walk slowly and children who take up less space) are instructed to evacuate via fire elevators and the other 90% of evacuees (young men and women who move fast) use the stairs, the evacuation time can be reduced to a minimum. Some improvements in the design drawing result in the enhanced efficiency of the proposed strategy. The findings of this work are of great significance for the optimization of the structural design of large public buildings and provide some references for emergency evacuation.