In order to improve the tribological properties of sea frictional key components, uniform and gradient CrCN coating were deposited on 316L stainless steel and single crystal silicon by multi arc ion plating technique. The microstructures, mechanical performance, corrosion resistance and tribological properties in seawater were systematically investigated by XRD, XPS, SEM, Scratch test system, nano-indentation, 273A electrochemical workstation and ball-on-disc tribol-meter. The results showed that the grain size, crystallinity of Cr7C3(421), mechanical performance and corrosion resistance of gradient CrCN coating were better than uniform CrCN coating. Friction coefficient and wear ratio in seawater of gradient CrCN coating were lower than uniform CrCN coating, which indicates the gradient CrCN coating has a good tribological properties than uniform CrCN coating.