Objective To improve the surface properties of 45# steel. Methods Using IPG fiber laser YLR-3000 Laser Processing System, laser cladding of self-fluxing Ni-based WC Powders was conducted on the surface of 45# steel using different process parameters. Comparative analysis was conducted on the macroscopic surface (Flatness, surface hardness, cracks), metallurgical structure and distribution of microhardness of the cladding layer. Results When the laser power was 1200 W, scanning speed was 2 mm/ s, and powder feeding voltage was 7 V, the cladding layer had relatively smooth macro surface, and the average Rockwell hardness of the cladding layer was about 2. 5 times that of the matrix. The microstructure analysis showed that there were no defects such as cracks and holes in the cladding layer and the interface, the middle and upper part of the cladding layer had fine grains, the grains were dendritic and equiaxed along the interface of the cladding layer and the substrate, the structural performance was good, and the metallurgical bonding between the cladding layer and the substrate was relatively strong. The microhardness distribution of the cladding layer was relatively even, and increased by about 1. 5 times as compared to the substrate. Conclusion The mechanical properties of 45# steel surface were improved. Laser cladding of self-fluxing nickel-based tungsten carbide powder on its surface has therefore feasibility and research value.