Transformation behavior between localized and general corrosion of die‐cast AZ91D magnesium alloy in anodizing processes was investigated by galvanostatic polarization. The results revealed that, at electric current density 5, 10, and 20 mA/cm2, a localized corrosion state appears on the specimen surface in the initial stage (10 min), and is changed into general corrosion with the galvanostatic measurement time. On the other hand, the increase in electric current density has caused the increase of the corroded area on the specimen surfaces at the same galvanostatic measurement time. In comparison, the appearance of localized corrosion based on general corrosion can be attributed to the localized absorption along with enhanced activity and reactivity of Cl− at the higher electric current density (10 and 20 mA/cm2). Meanwhile, the penetration of Cl− throughout the corrosion products has caused the destruction of the integrity of these corrosion products, which promotes the continuous growth of the localized corrosion pits under the galvanic effect.