The two kinds of composites, including nano-nitrile butadiene rubber (NBR)/epoxy resin (EP) and nano-acrylate/EP composites were prepared with the three-roll mill. The effect of nano-particles on the mechanical property of epoxy resin composites were investigated by tensile strength testing. SEM images were taken to characterize the decentralization of the nano-particles in the composites. Mechanical testing results were presented that the epoxy nano-composites has the higher tensile strengths after filling with nano-particles. The tensile strength of EP composites has been significantly improved with nano-NBR content 4 wt. % and the nano-acrylate content 3 wt. %, respectively. SEM results indicated that nano-particles can be evenly dispersed in the epoxy resin by the three-roll mill dispersion method.