Abstract: The preliminary mesoscale simulation was done for the hot spot formation of plastic bonded explosives(PBX) under shock loading with the combined method of the finite element and discrete element methods. The explosive crystals and binder are simulated using FEM and DEM, respectively. Simulated results indicate that hot spots focus on the binder region between crystals. The important factor of hot spot formation is the shock interaction between crystals and binder, the temperature of HMX is lower than that of binder, and the periphery temperature is higher than the inner temperature in HMX crystals.