Abstract: The nanocrystalline cobalt deposit with different structural characteristics and grain size were prepared by using different electro-deposition methods. The surface topography, and the size and the crystalline phase of the cobalt deposit were investigated by scanning elecrtron microscopy (SEM) and X-ray diffraction (XRD), respectively. The microhardness of the cobalt deposit was evaluated on MV-2T hardness tester. The friction and wear properties of the cobalt deposit were studied on a UMT-3M multifunctional friction and wear tester, and their worn surface were characterized by SEM. The results show that the size and crystalline phase of cobalt deposit, tribological properties and microhardness, were significantly affected by the electro-deposition methods. The cobalt deposit prepared by dual pulse electro-deposition had the smallest grain size, the highest microhardness and better wear resistance. The pin holes of the nanocrystalline cobalt deposit prepared by single-double pulse electro-deposition were the smallest. And this cobalt deposit also exhibited the best wear resistance and higher microhardness. These results indicate that the structure, anti-wear properties and microhardness of cobalt deposit can be controlled by controlling electro-deposition methods.