The (B2O3+WO3+C) Ni-based cladding layer has been prepared successfully by laser cladding on steel 45# substrate. The microstructure of the cladding layer was analyzed by scanning electron microscope, and the microhardness of the cladding layer was measured by microhardness meter. The result shows that laser power and(B2O3+WO3+C)powder content have a significant effect on the microhardness of the cladding layer. At a laser power of 1.8 kW, (B2O3+WO3+C) powder content of 15%, scanning speed of 2 mm/s and defocusing of 50 mm, the average microhardness of the cladding layer is as high as HV0.31300, which is about 6.5 times the average microhardness of the substrate, which greatly improves the hardness and wear resistance of the cladding layer.