Disclosed is a graphene polymer composite material, including a matrix resin, a filler and a plurality of nano-scaled graphene sheets. Each nano-scaled graphene sheet has a surface-modified layer formed of a surface modifying agent, which provides hydrophilic and hydrophobic functional groups used to form chemical bonds with the matrix resin and the filler, thereby greatly improving strength of junction cohesion. The filler helps the graphene sheets to contact each other so as so to increase overall electrical conductivity and thermal conductivity. Since the graphene sheets are uniformly dispersed in the matrix resin, the composite material of the present invention possesses excellent mechanical property, anti-oxidation, acid-base resistance, high electrical conductivity and thermal conductivity. Therefore, the composite material is suitable for the industries in need of high performance material.