The invention relates to a nickel-coated graphite sealing coating on the surface of a cast-iron workpiece, and a preparation method of the nickel-coated graphite sealing coating, and belongs to the technical fields of composite materials and thermal spraying. The bonding strength of the coating and a matrix is increased by taking a NiAl metal coating as a bonding layer, a nickel-coated graphite coating is sprayed on the surface as a self-lubricating coating, a stable abradable coating system based on the thermal spraying on the cast-iron surface is formed through combination, a gap between anair compressor and a cartridge receiver can be effectively filled, good impact resistance and thermal shock resistance are achieved, and therefore the working efficiency of the air compressor is increased; and the NiAl bonding layer is prepared through electric arc spraying for wires, and the large-particle-size nickel-coated graphite sealing coating is prepared through flame spraying. The double-layer coating system prepared by the preparation method is compact in microstructure; high bonding performance between the coatings and between the coating and the cast-iron matrix is achieved; and graphite phases are uniformly distributed in the coating. Meanwhile, the nickel-coated graphite sealing coating on the surface of the cast-iron workpiece has the advantages of being low in graphite oxidation loss rate, simple in process, low in cost, high in efficiency, high in repeatability, suitable for large-scale production, and the like.