The preparation of graphene and copper composite line and the application technology of power transformer are the research hotspots for power equipment. As an ideal reinforced phase composite material, graphene has unique two-dimensional structure, high strength, high electrical conductivity and high thermal conductivity and other super mechanical and functional properties. The combination of graphene and high-purity metal copper greatly improves the tensile strength of the composite material while improving the conductivity of the traditional copper material. Chemical vapor deposition (CVD) is an important method to prepare graphene/copper composites. In this paper, the influence of CVD process parameters of graphene on the surface of copper foil is studied, which lays a foundation for improving the overall conductivity of graphene copper material. For the preparation of graphene on the copper crystal surface substrate by CVD method, the temperature is more suitable at about 1000 degrees Celsius. Compared with polycrystalline copper foil, the addition of graphene increased the overall conductivity of graphene copper foil by 3.7% IACS. The introduction of large-area and high-quality graphene on the surface of copper matrix is conducive to achieving good electrical and mechanical properties of graphene copper electromagnetic wires for power transformer.