Abstract: One of the best ways to control the crack propagation during rock blasting is to drill a guide-hole between the charging boreholes. The blasting process is composed of two consecutive stages, i.e., the dynamic stage caused by the stress wave and the static stage caused by the explosion gas. Based on this cognition, a general damage model for blasting damage is established. The blasting-induced crack propagation around two boreholes in the PMMA (polymethyl methacrylate) when detonated simultaneously is numerically simulated. The different cracking patterns under the configurations of no guide-hole, an ordinary circular guide-hole and a notched guide-hole between two charging boreholes are examined. The numerical results agree well with the experiments in the laboratory, which verify the effectiveness of the configured guide-hole in controlling the crack coalescence between two boreholes and confirm the validity of the proposed model in predicting the blasting damage.