Abstract: Based on the theoretical analysis of gas adsorption and gas seepage in porous media, some new opinions on the law of gas migration in coal seam were proposed with experimental analysis. The results show that, for the gas in migration, coal structure has the storage-resistance effect, the dual functions of gas charging effect and gas hindering effect form the basic feature of coal matrix; adsorption reaction time, adsorption growth rate, adsorption equilibrium time and the maximum adsorption capacity are 4 key adsorption indexes between the coal samples; diffusion and seepage are two ways of gas migration in coal seam. When the gas pressure in the fractures or the large holes are higher than the gas pressure in the micro-nano-pore system, the gas migration velocity is dominated by gas seepage, otherwise, gas diffusion would be the main factor; the more developed the fracture, the more sensitive the coal body to the change of gas pressure drop, and the higher the gas desorption efficiency.