Digital image processing method is used as a tool to represent the heterogeneity of rock

which can be introduced into the finite element method; and a numerical model considering the real mesostructure of rock is established. By using this method to represent the heterogeneity of granite

a numerical specimen of granite is built to carry out uniaxial compressive tests. The influence of granite’s mesostructure on its deformation and strength is studied. The results show that the mesostructure of granite has an important effect on stress concentration under loading. The compressive strength of granite is evidently different when loading under different directions

and presents anisotropic behavior. But the influence of mesostructure of granite on its elastic modulus is very small. The digital image-based numerical method proposed provides an effective tool to study the mesomechanical behaviors of rock and rock-like materials.