Abstract: This paper studies the electrochemical corrosion behavior and mechanism of the commercial 55 % AlZn -Si and Zn coatings in 3.5 % NaCl aqueous solutions by cyclic voltammetry, polarization curves, corrosion potential and electrochemical impedance spectroscopy. The results showed that, the hot -dip 55 % Al -Zn -Si coatings exhibit better anti-corrosion performances and longer corrosion life than those of the hot-dip Zn coatings during the same long -tern immersion tests, due to the formation of compact aluminum oxide film and good corrosion resistance of Al.