Traditional melt-cast explosives still meet some challenges including weak inter-molecular interactions and poor mechanical properties,and molecular dynamics modeling process was carried out in Materials Studio to investigate the theoretical viscosity and mechanical reinforcement of melt-cast composite systems.The results show that the energetic crystals increased the viscosity of the continuous phase DNAN,and the anisotropic viscosity of continuous phase on crystal surfaces are related to different inter-facial interactions; attractive inter-molecular forces were found including the π-π conjugation stacking,hydrogen bonds and coordinate interactions between the explosive TNT and the polymeric modifier GAP-PUU; strong attractive interactions exist between the interfaces of TNT and the polymer,as well as between DNAN/RDX and APER,wherein van der Waals forces were found to play the main role,and these inter-facial interactions were found to reinforce the mechanical performance of the whole composite systems.The conclusions are of significance in the design and evaluation of advanced composite explosives.