Abstract: In order to improve the corrosion resistance of electrical pure iron, the Al Cr coatings were prepared on pure iron substrate by magnetron sputtering. The surface morphology, structure and element composition of the coatings were analyzed by XRD and SEM. The corrosion resistance of the electrical pure iron and the Al Cr coatings were analyzed by neutral salt spray test and electrochemical test. The results show that the coatings can be densified by doping appropriate amount of Cr element, and the Al Cr coating shows the best anti-corrosion performance when the Cr target power is 75 W.With the doping of Cr, the Al Cr coatings present different chemical compounds, such as Al₈Cr₅, Al₁₃Cr₂and other phases. The neutral salt spray and electrochemical test results show that the corrosion resistance of Cr-75 coating is the best. After 158 h of salt spray test, no corrosion phenomenon is observed. The resistance of Cr-75 coating is about 2 orders of magnitude higher than that of pure iron, and the corrosion current density is 7.4×10^-9A/cm², which is about 3 orders of magnitude lower than the pure iron(1.6×10^-6A/cm²). The potential difference between the pitting potential and the corrosion potential is the largest for Cr-75 coating(0.272 V). In addition, the anti-pitting performance for Cr-75 is the best, and the protection efficiency is 98.8%.