Abstract: The effects of weathering index on the electrochemical behavior of hot-rolled weathering steels were investigated by dynamic potential polarization curves and AC impedance spectrum. The results show that the six weathering steels did not form a multilayer film structure due to the formation of corrosion products in the 3.5% NaCl solution. The corrosion resistance was positively correlated with the weathering index (I). When the weathering index was between 0.57-11.34, the corrosion potential of the weathering steels increased with the increase of the weathering index, and in line with the relationship: E_corr=2.34·10^-4I²+0.007 9 I-0.685.