A novel numerical model for simulating fracturing process of the heterogeneous materials such as rock or rocklike material has been developed and implemented in the FLAC, which is the numerical code for the engineering mechanics analysis. A constitutive model that captures an essential component of brittle material failure, that is, cohesion weakening and frictional strengthening (CWFS) is improved by taking accounting the elastic modulus of element may degrade when the element failure. Furthermore, a new energy index, Local Energy Release Rate (LERR), is put forward to simulate energy release during failure process by tracking the peak and trough values of elastic strain energy intensity before and after brittle failure. The numerical model has applied to simulate the initiation, propagation and coalescence of cracks in the failure processes of brittle material. Using this numerical model, we studied the failure processes of simulated rock specimens with different heterogeneity. The results suggest that the model is a powerful approach to the study of macroscopic fracturing behaviour of heterogeneous material.