Abstract: Shock responses of PBX9501 explosive were modeled using material point method which was implemented in the Uintah computational framework. Two-dimensional simulation model was established based on the microstructure of PBX9501. Shock loading for the explosive was performed by a piston moving at a constant velocity. Simulation results indicate that under shock loading serious plastic strain appears on the grain boundary of HMX explosive. Simultaneously, the plastic strain energy transforms into thermal energy, causing the temperature to rise rapidly and some hot spots on grain boundary zones to form. The influence of shock strength on the responses of explosive was also investigated by increasing the piston velocity. It shows that shock strength has little effects on distribution of plastic strain and temperature, while their values increase with the increase of shock strength. Namely, the higher the shock strength is, the higher the hot spot temperature will be.