By simulating the accelerated corrosion test of Q235B carbon steel under the polluted marine atmospheric environment in Guangdong, the corrosion kinetics were studied using the weight loss method. The surface corrosion morphology of Q235B carbon steel was observed using 3D confocal microscopy and scanning electron microscopy. The electrochemical properties of the rust layer were studied using the potentiodynamic polarization curve, and the composition of the corrosion products was analyzed using X-ray diffraction (XRD). The results indicate that Q235B carbon steel is mainly subjected to uniform corrosion, and the microstructure shows two stages of corrosion pit formation and smooth corrosion pit, with the two stages alternating. In the simulated accelerated corrosion test of polluted marine atmosphere in Guangzhou, the corrosion products of Q235B carbon steel are mainly composed of α-FeOOH, γ-FeOOH, and Fe3O4. With the extension of the test period, the proportion of α-FeOOH and γ-FeOOH increases, while the proportion of Fe3O4 decreases.