Abstract: In order to study the corrosion behavior of transmission line under 30 mA leakage current, in this paper, the corrosion weightlessness of metallic materials under different SO₂ concentrations and different leakage currents is analyzed. When SO₂ concentration is relatively low, the effect of leakage current on corrosive weightlessness is not obvious; when SO₂ concentration is relatively high, leakage current will expedite the corrosion of metallic material and more metastable γ-FeOOH will accumulate on the surface. When γ-FeOOH accumulates to a certain extent, parts of it will convert to relatively stable α-FeOOH and Fe₃O₄ and the corrosion is mitigated by the stable products, which improves the corrosion resistance of samples.