Abstract: The Zn-Ni composite coating was prepared by electroless nickel plating on 40 Cr steel surface and powder zincizing by embedding method. The influence of zinc-nickel composite infiltration at different temperatures（370 ℃, 390 ℃,410 ℃, 430 ℃, 450 ℃） and different holding time（2 h, 4 h, 6 h） on the preparation of the coating was analyzed. The thickness, cross section morphology and composition of different samples were analyzed by metallographic microscope and scanning electron microscope（SEM with EDS）. The hardness from the surface of the infiltration layer to the substrate was measured by microVickers hardometer. The results show that after electroless nickel plating and powder zincizing, a two-layer composite coating containing zinc-nickel layer and zinc-iron layer with suitable thickness and uniform density can be obtained. Compared with the holding time, the zincizing temperature has a greater influence on the thickness of the zinc-nickel composite layer. The Vickers hardness of zinc-nickel composite coating can reach 450 HV, and its self-corrosion potential has a positive shift of 625 m V comparing with that of zinc-nickel coating, which can significantly improve the wear resistance and corrosion resistance of 40 Cr steel.