Al-Li alloys are widely used in aerospace industry owing to their low density and high specific strength, but they are facing corrosion challenges in marine environment. In this work, femtosecond laser ablation (FLA) technique is employed to modify the surface of Al-Li alloy in order to enhance the corrosion resistance, and the effects of FLA in the air (FLA-Air) and FLA in the water (FLA-Water) are compared. It is found that the FLA-Air treated surfaces are hydrophilic, while the FLA-Water treated surfaces are near superhydrophobic with contact angle of 140–150°. The FLA-Water surface, treated by using the laser power of 240 mW, shows superior passivation ability, and its corrosion current density is three orders of magnitude lower than that of the alloy matrix. The synergistic effect of hair-like porous nanostructure and high oxidation degree of the surface contributes to the superior corrosion resistance of the FLA-Water treated alloy. Our work provides a novel strategy for the effective corrosion protection of light metal surfaces.