Tea polyphenols and vitamin C are used as reducing agents that are introduced into nitrile–butadiene rubber (NBR) and NBR/graphene oxide (GO) latex systems, and the double bonds in the NBR and the GO sheet in NBR/GO are simultaneously hydrogenated and reduced through the synergistic hydrazine hydrate/hydrogen peroxide/copper sulfate catalytic system to prepare hydrogenated NBR (HNBR) and HNBR/reduced GO (RGO) nanocomposites. The degree of hydrogenation of the product is improved and the gel content of the product is reduced, which effectively solves the problems of the low degree of hydrogenation and high gel content in the diimide catalytic hydrogenation system. At the same time, the HNBR and HNBR/RGO nanocomposites, which are co-reduced by tea polyphenols and vitamin C, have good thermal stability and mechanical properties. Tea polyphenols are more likely to participate in the hydrogenation reaction. The degree of hydrogenation of the NBR double bonds is higher than the amount of reduction occurring within the GO sheet with the addition of tea polyphenols.