Abstract: Molecular dynamics (MD) method was used to simulate the structure and properties of HMX-based four components composite material, the other components were TATB, F2311(binder) and paraffin (desensitized agent). Similarly, MD was used to simulate 3 HMX-based two components explosives (HMX/TATB, HMX/F2311and HMX/paraffin) to investigate the effects of components on base explosive. To make further elucidation of mechanism and effect of desensitized agent, the first principle of quantum chemistry, DFT were used to calculate the supermolecular system, HMX/paraffin. Furthermore, the detonation heat and velocity of them were computed according to theoretical formulas. Results show the elasticities of composite materials are increased and the effect of binder is largest in three additives on mechanical properties of HMX. Additives can decrease the detonation heat and velocity of base explosive more or less. It is found that the interaction of desensitized agent and HMX is rather weak so electronic structure factor is not the main cause of desensitization of PBX. Therefore, in the theoretical design of PBX, the complicated effects of components should be taken into account.