Abstract: Based on the energy conservation theory, the approximate calculation formula of elastic potential is deduced through theory analysis, then according to the theory of gas dynamics, the quantitative analytic calculation method of incident overpressure and reflection overpressure generated from the gas outburst shock wave is achieved. Finally, an example analysis results show that the calculation formula and the measured values are coincident. The analytic calculation method considers the comprehensive effect of the coal-seam's parameters, which can provide the reference for the calculation of tunnel facilities force.