In this study, we prepared the 3-aminopropyltriethoxysilane (APTES) functionalized MWNTs/epoxy composites by electron beam (EB) irradiation process. The modified MWNTs were characterized with SEM-EDS and FTIR. The gel content and conversion rate of epoxide groups of the EB cured pure epoxy resin and the APTES functionalized MWNTs/epoxy composites were measured and discussed. And the mechanical properties of the EB cured composites were also characterized. With addition of 0.25wt% APTES functionalized MWNTs, the Vicker’s hardness of the EB cured composite increased 100.02% compared with pure epoxy.