First, this paper presents the commonly used integrated method to prevent the mine fire disaster, i.e. close the fire zone and inject inter gas. Then it establishes a three-dimensional physical model of the fires roadway by using Gambit. Through the three-dimensional numerical simulations of gas in fire zone by using fluent software, it gets the distribution of the temperature and component(CH4,O2) concentration fields in the fire zone after closing the fire zone for 30 s (when injecting inert gas). Finally, according to the simulation results, it analyzes the migration law of the gas in the fire zone, and gets the possibility of a gas explosion in the fire zone closed for 30 s, providing preparations for study of the subsequent behavior to prevent the disaster in the closed fire zone such as injecting inert gas.