In order to improve the corrosion resistance of AZ31 magnesium alloy, the amorphous/nanocrystal Al-Cr-Fe film has been successfully prepared on AZ31 magnesium alloy by double glow plasma technology. The amorphous/nanocrystalline consists of two different regions, i.e., an amorphous layer on outmost surface and an underlying lamellar nanocrystalline layer with a grain size of less than 10 nm. The corrosion behavior of amorphous/nanocrystalline Al-Cr-Fe film in 3.5% NaCl solution is investigated using an electrochemical polarization measurement. Compared with the AZ31 magnesium alloy, the amorphous/nanocrystalline Al-Cr-Fe film exhibits more positive corrosion potentials and lower corrosion current densities than that of AZ31 magnesium alloy. XPS measurement reveals that the passive film formed on the Al-Cr-Fe film after the anodic polarization tests is strongly enriched in Cr 2 O 3 , Fe 2 O 3 and Al 2 O 3 at outer surface of the film and in the inner layer consists of Cr 2 O 3 , FeO and Al 2 O 3 .double glow sputtering, Al-Cr-Fe film, AZ31 magnesium alloy, corrosion behavior, amorphous/nanocrystal