Abstract: In this paper,triaxial compression tests are carried Out with various confining pressure and pore pressure.The results proved that the mechanical properties and mechanical response of gas-absorbent coal are influenced bothby absorbed gas and free gas. One of the influence is the mechanical effect of gas prereure as body force,and theother is the non-mechanical effect of absorption and deserption of gas.Therefore,in the study of the mechanismof out bursts and gas flowing in mined coal seams,both the mechanical and non-mechanical effects of gas on themechanical response must be considered.