Abstract: The corrosion behavior of three kinds of low alloy high strength steel (Q550 steel, 40Cr steel, 35CrMoA steel ) and Q235 carbon steel exposed in Chengdu atmospheric environment for one year was studied by atmospheric exposure test and electrochemical test. The results showed that the corrosion rates of Q550 steel, 40 Cr steel, 35 CrMoA steel and Q235 carbon steel in Chengdu atmospheric environment were 80.07,83.39,80.66 and 138.98 g/(m²·a), respectively, and the maximum pit depths were 66.01,40.86,49.30,45.18 μm, respectively. The composition of rust layer on the surface of the four samples was basically the same, mainly composed of γ-FeOOH, α-FeOOH, Fe₂O₃ and Fe₃O₄. The content of α-FeOOH in the rust layer on the surface of low alloy high strength steel was higher than that of Q235 carbon steel. The rust layer resistance of Q235 carbon steel was higher than that of three kinds of low alloy high strength steel. However, due to the loose corrosion products and the failure to completely cover the metal matrix, the corrosion rate was larger, that was, the corrosion resistance of three low alloy high strength steels was better than that of Q235 carbon steel.