Abstract: The microstructures,surface morphology and composition of nanocrystalline Ni-Co alloy and nano SiC/Ni-Co composite coating prepared by pulse electrodeposition were studied by XRD，SEM and EDS. The corrosion characteristics of nanocrystalline Ni-Co alloy and nano SiC/Ni-Co composite coating were comparatively tested by the soak method and the electrochemical polarization method，respectively. The experimental results indicate that typical nanocrystalline Ni-Co alloy and nano SiC/Ni-Co composite coatings can be synthesized by pulse electrodeposition，and with the increasing of the nano SiC particles，the grain size of nano SiC/ Ni-Co composite coating is diminished while the microhardness is increased. The nano SiC/ Ni-Co composite coating has better dispersion and it exhibits better corrosion resistance in 3.5 wt% NaCl and 5 wt% HCl solution than the nanocrystalline Ni-Co alloy. The surface morphology of all samples after corrosion in 3.5 wt% NaCl solution shows good corrosion resistance,while the samples show spot corrosion in 5 wt% HCl solution.