Abstract: Serious oxidation corrosion happened to the polar line of the electric precipitator during use process, and it affected the dedusting effect of the electric precipitator. The corrosion failure reasons of the polar line of the electric precipitator were analyzed by macrographic examination, chemical composition analysis, corrosion product analysis and metallographic examination. The results show that: the polar line of the electric precipitator was oxidized under superheated condition; the oxidation coatings on the material surface were destroyed by the chloride element, so the metal dissolution in the reaction areas was accelerated, and the retarded effect of the oxidation coatings was reduced, which led to the corrosion product desquamation on the surface of the polar line of the electric precipitators; the oxidation corrosion rate of the polar line increased, and finally the polar line was getting thinner to failure.