Abstract: The corrosion characteristics of ultra-low carbon bainitic steel for bridges in the marine environment were investigated based on experiment. The mechanical properties and corrosion behavior of marine bridge steels were investigated through mechanical property tests, salt spray corrosion experiments, rust layer morphology and physical phase analysis of corrosion products. The results show that the ultra-low carbon bainitic steel for bridges can form a dual-phase structure consisting of polygonal ferrite block（QPF） and granular bainite（GB） after TMCP+tempering, which can match the strength and toughness, while the enrichment of Cu elements hinders the entry of Cl^-, reduces the corrosion rate and promotes the formation of dense rust layer.