In this study, the effects on the tensile strength of E-glass/epoxy composite materials produced using graphene nanoparticles were investigated experimentally. The graphene nanoparticle composite was used at 0.1%, 0.3%, and 0.5% by weight of the composite plate. The effect of angled orientation and addition of nanoparticles on the composite sandwich structures were examined. The load carrying capability of composite was significantly influenced by graphene nanoparticles. Experimental results and scanning electron microscopy analysis of the present study indicate that failure was mainly caused by fiber and matrix failure. Matrix properties were improved by adding graphene nanoparticles. The amount of 0.1% graphene additive led to 20% increase in the composite strength. Optimum amount of graphene was determined experimentally.