Due to the high bonding strength, high hardness, and good corrosion resistance, sherardizing is suitable for corrosion protection of high-strength steel parts. However, its application is limited because the low sherardizing efficiency, and high processing temperature which would affect the mechanical properties of the substrate materials. In the present article, sherardizing was conducted to HT250 gray cast iron. The substrate was treated by high energy ultrasonic shot peening before sherardizing, and nanoscale active agents were added into the filler during sherardizing process. Then the sherardizing temperature was decreased to 380 ℃. After that, microstructure and composition analysis were conducted to the sherardized coating. The corrosion resistance of the sherardized coating at different depths was investigated through electrochemical method. At last, the corrosion resistance of passenger vehicle brake discs surface treated with sherardizing and zinc flake painting was compared through thermal treatment + neutral salt spray test. The results show that the sherardized coating is composed of δ phase on the surface and Γ/Γ1 phase near the substrate, which has good corrosion resistance. The corrosion resistance of the sherardized coating decreases slightly from surface to the interface with substrate, but the entire sherardized coating shows a good cathodic protection effect on the substrate. The brake disc with sherardized coating exhibits better high-temperature resistance and coverage than that with zinc flake coating, especially in areas such as holes and ventilating duct.