Abstract: In order to improve the surface properties of 45 steel, Ni-based Si C composite coating was prepared on the surface of 45 steel by laser cladding with hexagonal boron nitride（h-BN） as additive. The effects of different mass percentages of h-BN on the microstructure, corrosion resistance, microhardness and wear resistance of nickel-based Si C composite coatings were investigated by means of X-ray diffractometer, scanning electron microscope, microhardness tester,electrochemical workstation and friction and wear tester. The results show that the main phases in the Ni-based Si C coating are γ-Ni, FeNi₃, Si C, Cr₂₃C₆ and Cr₇C₃. After adding h-BN, the strengthening phases such as Cr₂B, Ni₄ B₃ and Si₃ N₄ are formed.The phases exist in the form of crystals in the coating, and the crystal structure of the coating is mainly dendritic crystal,cellular crystal and reticular eutectic structure. The corrosion resistance, microhardness and wear resistance of the coating increase first and then decrease with the increase of h-BN mass fraction. When the addition amount of h-BN is 1.5 wt%, the passivation film is the most stable, the corrosion rate is lowest, the corrosion resistance is best, and the average microhardness is highest, which is 1.8 times higher than that of the substrate. The wear mechanism is abrasive wear, which has the best wear resistance and friction reduction performance.