The theoretical investigation of heat dissipation for polymer-bonded explosives (PBXs) is in high demand in explosive design in terms of safety and realibility, particularly as lack of effective experimental measurements. Here, we investigate the fundamental understanding of thermal transport across the heterogeneous interface between HMX and PVDF, by using the diffuse mismatch model and anharmonic inelastic model. This work explores the interfacial thermal conductance viaab initiocalculation and derived phonon dispersions, phonon group velocities. For HMX-PVDF interface, it is shown that low-frequency phonon modes (especially lower than 10 THz) and two-phonon elastic processes play dominant roles in the interface thermal transport. Furthermore, we present the calculated interfacial thermal conductance as a function of temperature. The thermal conductivity of mixture HMX-PVDF system is analyzed with an effective medium approximation model. From these calculations, we give the thermal transport properties predictions of PBX for thermal conductivity enhancement and provides fundamental microscopic insights into phonon transport physics in PBX.