Various geometric microstructures on aluminum alloy surfaces were fabricated simply through SiC paper rubbing, and the wettability of the obtained surfaces was investigated thoroughly. The water contact angle increased firstly with the increasing particle size of the sandpaper, and then declined with further increase of the grits size, exhibiting a hydrophilic-hydrophobic-hydrophilic transition. The effect of surface geometric microstructure on the wetting behavior of aluminum alloy can be well rationalized in terms of the Cassie-Baxter model by considering the surface energy gradient. The present results not only enhance the in-depth understanding of the mechanism for the significant role of surface microstructure on the wettability of aluminum alloy, but also explore promising applications of versatile metallic surface in industries. (C) 2014 Elsevier B.V. All rights reserved.