The invention discloses a graphene doped Cu/Cu2O nano photocatalytic coating and a preparation method thereof. The method includes: 1) pretreating a workpiece to remove dust, oil dirt and rust on thesurface of the workpiece; 2) preparing a graphene doped Cu/Cu2O composite slurry; 3) pressing the slurry on the surface of the pretreated workpiece through a mechanical roller to form a base layer; 4)adopting a vacuum induction sintering method, placing the workpiece with the formed base layer in a graphite integrated forming sintering mold, maintaining the pressure after the density of a pressedblank does not change any more, and starting sintering to form a preset layer on the surface of the workpiece; and 5) carrying out electron beam welding on the preset layer to obtain the graphene doped Cu/Cu2O nano photocatalytic coating. The method provided by the invention puts forward solar irradiation of the graphene doped Cu/Cu2O nano photocatalytic coating by a solar concentrating device, can solve the problem of shortening the forbidden bandwidth of a catalyst to expand an absorption spectrum to visible light so as to improve the solar energy utilization rate.