The corrosion resistance of 5083 aluminum alloy after refining with nano-CeB6/Al inoculant was investigated by 3.5 wt% NaCl solution, compared with that of as-cast alloy and cold-rolled alloy. It was found that nano-CeB6/Al inoculant showed significant grain-refining effect on 5083 alloy and the corrosion resistance of 5083 Al alloy was improved as well. The results of potentiodynamic polarization tests showed that the polarization resistance of refined alloy was higher than that of as-cast alloy and cold-rolled alloy, together with more positive breakdown potential value. The corrosion rate was dependent on the grain size following a power law type relationship, which was attributed to the reduced precipitate on the grain boundary.