Abstract: In order to reveal the distribution varied law of the gas in the fully-mechanized heading gateway during the heading period, taking the fully-mechanized heading face of No.12205 upper entry in Xinzheng Coal and Electric Power Company Limited as a study object, based on a Darcy seepage law, a dynamic seepage model of the seam gas in the fully-mechanized heading face was established. A finite volume method was applied to solute and obtain the seam gas pressure field and gas desorption rate field of the fully-mechanized heading gateway. Based on the circumstances, the gas emission rate formula of each gas emission source in the fully-mechanized heading face within heading advance period and the heading support period was analyzed and reduced. Based on the CFD dynamic grid technology, a gas diffusion unsteady calculation model of the fully-mechanized heading face was established and was applied to study the time-space evolution process of the gas concentration field within the fully-mechanized heading gateway during the heading process. The study results showed that the gas concentration within the fully-mechanized heading face during the heading advance period would be no obviously increased or decreased. Within the heading support period, the gas concentration in the fully-mechanized heading face was obviously reduced in tendency. The reliability of the numerical simulation results was proved by the site data measured.