Abstract: Molecular simulation technology can explore the reaction mechanism and the microscopic parameters of internal structure of polymer systems from the atomic scale to discuss the factors affecting the macroscopic properties of polymer composites. In this paper, the material system design and structure-performance correlation of epoxy resin matrix composites were studied. The current research of molecular simulation technology for the cross-linked network structure of epoxy resin and the mechanism of nanoparticle reinforced epoxy resin systems were summarized. The latest research results of scientific issues such as micro-interface and structural design of carbon fiber/epoxy composites were introduced, and the guiding significance and research strategy of molecular simulation methods in the future development of high-performance polymer matrix composites were proposed.