Abstract：A digital image based characterization method of rock¢s heterogeneity is developed according to the theory of digital image processing. In the proposed method，digital image processing method is used as a measurement tool to represent the actual spatial distribution of different materials and components in the rock samples. The heterogeneity described by this method is approaching to the actual heterogeneity of rock，which is mapped into the grid of finite element method(FEM). This characterization method is incorporated into rock failure process analysis(RFPA) code；and a numerical model that can actually reflect rock¢s heterogeneity is established，which overcomes the shortage that statistic theory is used to describe the heterogeneity of rock in traditional FEM. By simulating two regular laboratory tests(uniaxial compression and uniaxial tension tests)，real failure processes of granite are visually observed. The simulation results show that heterogeneity of rock has a great influence on its mechanical function and failure processes. This model provides an innovative method for the investigation on mechanical feature and failure mechanism of heterogeneous material such as rock，concrete and so on.
