The invention discloses a graphene oxide/polystyrene composite material synthesized by a novel atom transfer free radical technology. The material is a graphene oxide-based composite material comprising graphene oxide serving as a main body and polystyrene serving as a polymer chain, wherein nano graphene oxide is obtained by oxidation treatment, and the polystyrene is covalently bonded to the surface of nano graphene oxide. A preparation method of the composite material is further disclosed. The preparation method of the graphene oxide composite material provided by the invention can improvethe problems that a product in a conventional preparation process is difficult to clean, severe in pollution and the like, and solves the problem that the graphene oxide is difficultly chemically bonded to macromolecules; the composite material has the characteristics of environmental protection, simple operation, low cost and the like without affecting the performance of the composite material. The preparation method disclosed by the invention is simple in step, easy to operate and high in efficiency, and preparation conditions are mild and easy to control.