Due to high grain boundary density,nanocrystalline(NC) functional coatings exhibited unusual mechanical,physical and chemical properites.The tribological and corroison performance is very important to their engineering applications.In this paper,Nanocrystalline Ni and Co coatings with different grain size were prepared by electrodeposition method.The microstructure of the NC coatings were studied by X-ray diffraction (XRD) and transmission electron microscope (TEM).Effect of grain size nanocrystallination on the tribological and corrosion behavior of NC coatings were investigated.Results show that grain size nanocrystallization in NC coating exhibited different effect on the tribological behavior with regard to the Ni (fcc structure) and Co (hcp structrue) coatings,which can be attributed to their different phase structure and corresponding wear mechanism.