Abstract: According to the structure of the big public building, population distribution, and characteristics of the fire stretching, first of all the space of the building is modeled. Then the mathematical model of the behavior of the population dispersion is established. By the relation database According to the structure of the big public building, population distribution, and characteristics of the fire stretching, first of all the space of the building is modeled. Then the mathematical model of the behavior of the population dispersion is established. By the relation database technology and Mapinfo system, the computerized simulation system of the population dispersion behavior during the fire of a big public building is developed and exemplified.