Aluminum alloy was treated into different surface roughness by anodize oxidation method and sanding method, covered with stearic acid coating materials on the aluminum alloy substrates, the samples with different surface wettability were formed. The effect of wettability change on corrosion resistance and vulnerability was studied. The results showed that when surface roughness was increscent, surface contact angle was also increscent and the wettability was depressed, which could improve the corrosion resistance of aluminum alloy in weak acid, weak alkaline, salt solutions and vulnerability. When the contact angle was greater than 150°, the surface wettability reached the lowest figure, resulting in surface superhydrophobicity, the corrosion resistance of aluminum alloys was better, but weight-loss test method showed the corrosion resistance of aluminum alloy was poor in strong acid or strong alkaline. Vulnerability has been greatly improved when the contact angle was greater than 150°.