There is limited studies available on the corrosion of carbon steel in freshwater surroundings. Herewith, plates of two ship steels CCSA and Q235B steel were exposed to different sites such as the atmosphere, waterline, and underwater in freshwater surroundings of the Changjiang River (Yangtze River) for 0.5, 1, 2, 3, 4, and 7 a, then there corrosion behavior was assessed by means of morphology analysis, mass-loss measurement, XRD, and electrochemical techniques. Results show that the two carbon steels suffered from significant corrosion in the freshwater surroundings of the Changjiang River, exhibiting nearly the identical corrosion morphology. Their corrosion processes follow a power function law. After 7 years, the corrosion rates of CCSA were found to be 8, 77 and 40 μm·a^-1 in the atmosphere, waterline, and underwater, respectively, while the corrosion rates of Q235B were 9, 80, and 41 μm·a^-1 in the same conditions. Among others, the corrosion on the waterline was the highest. The composition of the corrosion product of the two carbon steels was similar, primarily including SiO₂, α-FeOOH, γ-FeOOH, Fe₂O₃ and Fe₃O₄/γ-Fe₂O₃. Based on the comprehensive electrochemical analysis results, CCSA demonstrated better corrosion resistance than Q235B. Regarding to the test results in various test sites of freshwater surroundings of the Changjiang River, the corrosion rate of the carbon steels may be ranked in descending order as follows: waterline> underwater > atmospheric.