Numerical simulation and related models for HMX based PBX explosive machining were performed and studied by using LS-DYNA. Tool forces with various cutting parameters were computed for HMX based PBX explosive,and the calculational results agree well with the experimental results. Results show that the plane strain model is reliable for simulation of explosive machining when cutting width is far greater than cutting layer thickness. Effective stress failure criterion is appropriate for simulating chip separation of explosive. The tool force increases with increasing of depth of cut and feed rate,and cutting speed has no obvious effect on tool force. Depth of cut affects tool force most greatly among the three parameters.