Abstract: The corrosion behavior of 550 MPa weathering bridge steel in simulated industrial atmosphere was investigated by cyclic immersion corrosion tests. The microscopic morphology, phase composition of corrosion products, cross section morphology and element distribution of rust layer were observed and analyzed by means of scanning electron microscope, X-ray diffraction and electron probe. The mechanism of atmospheric corrosion resistance of high-strength weathering bridge steel was also discussed. The results indicated that the corrosion weight loss rate of Q550qENH-A steel and Q550qENH-B steel decreased rapidly at the initial stage and tended to be stable at the later stage with the extension of corrosion time in the simulated industrial atmosphere, and the corrosion resistance of the two kinds of weathering steels were better than that of Q345B. Cr and Ni were enriched in the rust layer of two kinds of weathering steels, which promoted the formation of α-FeOOH and improved the stability and compactness of the rust layer structure, thus the blocking effect of the rust layer on the corrosion medium was enhanced. Therefore, the weathering steels showed excellent atmospheric corrosion resistance.