Abstract: In order to ensure safety production and reduce gas explosion accidents effectively in coal mine,this article analyzes influencing factors of gas explosion based on the three classes of hazards theory,then builds three classes of hazards system of gas explosion according to the system engineering theory,and analyzes the causality among the factors within the system.On this basis,the SD model of gas explosion three classes of hazards system is built by using theory and method of system dynamic.Then using Vensim software,simulation and prediction of three classes of hazards system of gas explosion in a coal mine are done,which gives some theoretical guidance for coal mine safety production and dangerous source control.