The invention discloses an oxygen-containing functional group gradient distribution reduced graphene oxide/graphene foam composite and an application thereof to vanadium redox batteries, belonging to the field of battery materials and energy storage. Graphene foam is obtained by a chemical vapor deposition method, a three-dimensional graphene foam and graphene oxide aerogel structure is obtained in combination with graphene oxide aerogel preparation and metals are utilized for gradient reduction, thus achieving integration of high conductivity of a thee-dimensional network of graphene and graphene oxide with abundant oxygen-containing functional groups. The composite has the advantages and beneficial effects that by using the material as the electrode material of the vanadium redox batteries, the electrocatalytic activity and electrochemical reversibility of the V<2+>/V<3+> and VO<2+>/VO2<+> oxidation reaction can be improved, the charge transfer resistance can be reduced, the energy efficiency of the vanadium redox batteries can be improved and the cycle lives of the vanadium redox batteries can be prolonged; the composite has the characteristics of simplicity and convenience in operation, high yield and easiness in structure adjustment and control and has a terrific application prospect.