In order to study the deformation and destruction law under hydro-mechanical coupling of coal

the relationship between macroscopic mechanical parameters and microscopic parameters of coal is discussed seriously by compression and tension test numerical simulation with PFC2D. Simulation of conventional triaxial test under different confining pressures and gas pressures are performed on coal with parallel bonded model and the inferred relationship. The comparative error is analyzed between test results and simulated results; and the changing law of coal macroscopic mechanical parameters is summarized. The results show that: The relationship inferred by numerical simulation can simulate the coal mechanical characteristics well and control the error less than 10%. With the improvement of confining pressure

the compressive strength

residual strength and elastic modulus show a trend of increase

and the Poisson’s ratio and the angle of coal fracture decrease

so as to prove that the confining pressure can strengthen the stiffness and strength of coal. That the compressive strength

residual strength and elastic modulus continuously decrease and the Poisson’s ratio and the angle of coal fracture increase with the gas pressure increasing shows the weaken effect on the stiffness and strength of coal.