Abstract: WC-graphene oxide(GO)/Ni composite coating was fabricated by vacuum cladding technique. The microstructural change and phase composition of the coating at different temperatures were observed and analyzed by scanning electron microscopy, energy dispersive spectroscopy and X-ray diffractometer. The results show that the WC-GO/Ni composite coating with dense microstructure and good metallurgical fusion with the matrix was successfully fabricated on the ZG45 substrate. There are four sub-layers from the coating surface to substrate, they are composite layer with about 1.5 mm thickness, transition layer with about 360 μm thickness, diffusion fusion layer with about 50 μm thickness and diffusion affected layer with 100 μm thickness. The main phases of WC-GO/Ni composite coating are Cr₇C₃, FeNi₃, WC, Cr₂₃C₆, Ni₃Si, C, Fe₇W₆, γ-Ni solid solution. FeNi₃ and Fe₇W₆ are dispersed in the metallurgical fusion zone, and the main phase of the diffusion affected zone is pearlite. The phase size of the composite zone is smaller than that of the interface zone. The changing of metal particles at composite area precedes that at the interface area. The clusters (Cr₇C₃/Cr₂₃C₆) formed on the incompletely melted metal particles surface and grew into needle shape. The needle carbides are embedded in the Ni-based solid solution among the coating.