Abstract: In order to investigate the reinforcement and modification effects of graphite oxide (GO) on blending rubber, GO was synthesized by modified Hummers method, and GO/natural rubber (NR)-nitrile-butadiene rubber (NBR) composites were fabricated by latex co-coagulation technology firstly. Then, SEM, FTIR, XRD, swelling tests and mechanical property tests were employed to characterize the morphologies, structures and mechanical properties of GO, NR-NBR vulcanized rubber and GO/NR-NBR composites. The results show that the GO obtained contains a large amount of oxygen-containing functional groups, the oxidation effect is good; GO is homogeneously dispersed in rubber matrix, and the roughness of stretching section for GO/NR-NBR composites improves obviously. The apparent cross-linking density of the composites increases for the filling of GO. The mechanical properties of GO/NR-NBR composites improve with GO content increasing. When GO content is 3.0wt%, the tensile strength, tensile stress at 100% and Shore A hardness of GO/NR-NBR composites increase by 53.3%, 67.3% and 10.5%, respectively, and the elongation at break decreases by 9.6%.