Abstract: In order to simulate the mechanical properties of coal containing gas under the condition of in-situ stress variation in front of working face, RFPA^2D-Flow software is used in this paper to study the law of deformation, fracture process of coal containing gas under axial loading and lateral unloading of biaxial loading, and we discuss the effect of initial confining pressure, initial axial pressure and unloading rate on the deformation and failure of the specimen. The research results show that: in the direction of loading and unloading, the axial stress and the transverse stress increase linearly in the initial stage; when the stress reaches to the ultimate strength of the coal, the deformation and fracture of the coal will lead to a sharp stress drop, until the coal sample loses its bearing capacity; the greater the initial confining pressure and axial pressure, the smaller the unloading rate, the greater the ultimate compressive and tensile strength and the strain that coal can bear. The ultimate strength and strain are linearly related to the initial confining pressure and the initial axial pressure, however, the relationship between these mechanical parameters and the unloading rate shows a stepwise shape. With the increase of the loading rate, the ultimate strength and strain reduction rate decrease gradually.