tThe epoxidized natural rubber (ENR) as an interfacial modifier was used to improve the mechanical anddynamical mechanical properties of NR/silica composites. In order to reveal the interaction mechanismbetween ENR and silica, the ENR/Silica model compound was prepared by using an open mill and theinterfacial interaction of ENR with silica was investigated by Fourier transform infrared spectroscopy(FTIR), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), X-ray diffrac-tion (XRD) and stress–strain testing. The results indicated that the ring-opening reaction occurs betweenthe epoxy groups of ENR chains and Si-OH groups on the silica surfaces and the covalent bonds are formedbetween two phases, which can improve the dispersion of silica in the rubber matrix and enhance theinterfacial combination between rubber and silica. The ring-opening reaction occurs not only in vulcan-ization process but also in mixing process, meanwhile, the latter seems to be more important due to thesimultaneous effects of mechanical force and temperature.