Abstract: To solve the problems of low surface hardness and poor wear resistance of nickel copper (NiCu) alloy, the effects of WC with different particle sizes on the microstructure, microhardness, wear resistance and electrochemical corrosion resistance of the coating were studied. In this paper, the NiCu alloy coating, 60wt% coarse WC/NiCu composite coating and 60wt% fine WC/NiCu composite coating were prepared on A3 steel by laser melting deposition (LMD). The microstructure was characterized by scanning electron microscope, X-ray spectrometer and optical microscope. The microhardness and wear resistance of the coating were measured by microhardness tester and wear tester. The electrochemical corrosion resistance of NiCu alloy coating and composite coating were tested and analyzed by electrochemical workstation. The results show that the three coatings have formed a good metallurgical bond with the substrate, without obvious cracks and pores under the suitable parameters. The microstructures of cladding layer are mainly equiaxial and columnar, and the size of the grains is obviously reduced by the addition of WC. Compared with the NiCu coating, the microhardness of the coating with 60wt% coarse WC and fine WC increase by 62.1% and 81.1%, respectively, and the wear loss decrease by 84.8% and 94.3%, respectively. The wear mechanism is mainly abrasive wear. In 3.5wt%NaCl solution, the self-corrosion current density of the composite coating is 61% and 49% lower than that of NiCu alloy coating, respectively. The addition of WC significantly improves the performance of the NiCu alloy coating. The fine WC has a more obvious effect on the improvement of microhardness and wear resistance, and the coarse WC has an obvious improvement on the electrochemical corrosion performance.