Abstract: By controlling the concertration of NaWO₄ in plating solution, Ni-W gradient coatings were deposited on an aluminum alloy substrate by electrodeposition. The hardness profile of the gradient coating was determined. The results show that the concentration of element W increased along the growth direction. Ni-W gradient coating with homogenous and smooth surface, good adhesion to the substrate. Compared to the homogeneous Ni-W alloy, Ni-W gradient coatings had low friction coefficient, smooth worn surface with few surface spalling.