The corrosion behavior of Al100-xMox alloy (x = 10, 26, 50) films possessed fcc crystalline, amorphous and bcc crystalline phase structure were investigated in 3.5% NaCl solution. The corrosion behavior of Al100-xMox alloy films were controlled by the synergy of composition and phase structure rather than affected merely by the Mo content. The Al74Mo26 film with amorphous phase, compared with Al90Mo10 and Al50Mo50 films with solid-solution crystalline phase, displayed the superior corrosion resistance due to its stable passive film, homogeneous phase structure and proper Mo content. The corrosion mechanisms of Al100-xMox alloy films with different phase structures were illuminated systematically.