A multiscale modeling approach is proposed to account for the interfacial load transfer characteristics of epoxy nanocomposites. The localized stress evolutions in nanocomposites are examined with molecular dynamics (MD) simulations: the particle phase stress and the regional stress evolution in matrix medium. Plus, detailed atomic motions in the matrix phase are thoroughly studied with respect to the crosslink conversion. The distinct structural features in a highly crosslinked system induce a cohesive motion under the mechanical loading, thereby playing a favorable role in the internal load transfer from the matrix medium to the filler region. Further, interfacial load transfers with the curing conversion of epoxies are taken into account in the equivalent FE model with the weakened interface concept