Abstract: Selecting two mines and measuring coal seam gas pressure at different elevation,expansion energy in initial released gas and initial speed of methane diffusion of each point sample are tested in laboratory.It is found that there is a linear relationship among expansion energy in initial released gas and gas pressure and initial speed of methane diffusion,and the curve among them is achieved by using multiple linear regression to make the model of triadic relation.Considering initial speed of methane diffusion as constant,the safety gas pressure before rock cross-cut coal uncovering is achieved according to the curve,which provides a simple method for preventing coal and gas outburst.