The invention discloses a superhard self-lubricating coating tool and a preparation method thereof, and can be widely applied to cutting machining of dry cutting and refractory materials. A tool base material is high-speed steel, and a laminated superhard coating composed of a hard alloy layer, an aluminum oxide ceramic layer, a silicon nitride ceramic layer and a cubic boron nitride layer is arranged on the surface of a base body in sequence, a laminated coating has the self-lubricating effect; the laminated coating has the function of self-lubrication, and is prepared by adopting a plasma spraying method. The tool integrates high-speed steel, hard alloy, alumina ceramic and silicon nitride ceramic, cubic boron nitride and the laminated coating, the adding of a carbon nano pipe (CNTs) and a boron nitride nanopipe (BNHTs) improves the hardness, the wear resistance and the toughness of the coating, the whole tool not only has good toughness, but also has very high hardness and wear resistance; and in the cutting process, when the temperature is low, the graphene can have a lubricating effect, when the temperature is high, PbO, Mo and TiB2 can generate in-situ reaction to generate PbMoO4, TiO2 and B2O3 with a lubricating effect, so that the friction and abrasion of the tool in the cutting process can be reduced, and the service life of the tool is prolonged.