Abstract：A numerical simulation of the experiment on rock with preexisted cracks under compression is presented by using a rock failure process analysis code，RFPA2D. It is shown that most of the wing cracks initiate from the tips of preexisted cracks and eventually align themselves with the load direction. This result is of good agreement with the previous experiment. Though some numerical results do not agree with the experimental data completely，the heterogeneity of real rock material is simulated effectively with the models and parameters. By analyzing the stress field near the tips of cracks，it is shown that there is no essential influence of processing small holes on the failure mechanism of rock，although the small holes make the initiation angles of wing cracks become large and facilitate the initiation of secondary shear cracks. Lastly，a preliminary numerical analysis is made on the zigzag cracks.
