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At present, most of the research work aims to optimize the technological parameters of laser derusting under the condition of without damaging the metal substrate. The surface microstructure and corrosion resistance of the 35# carbon steel metal substrate were investigated by selecting an appropriate laser power density without affecting laser derusting effect. The surface microstructure and topography were characterized by scanning electron microscope, metallographic microscope, and white light interferometer. X-ray diffraction method was used to determine the surface structure of original new samples and derusting samples. The microhardness of the cross-section of the metal substrate after laser derusting was measured by Vickers microhardness tester with the load of 0.098 N. The polarization curves and galvanic corrosion measurement curves were used to characterize the corrosion resistance of laser derusting samples and original new samples. It is found that a heat-affected layer (HAL) of about 25-μm depth was formed on the surface of the metal substrate after laser derusting, which was composed of ferrite and pearlite-like. And the hardness of the HAL was increased. Comparing with the original new samples, the corrosion resistance of the derusting samples was significantly improved due to the change of the surface microstructure. As a common structural steel, 35# carbon steel is easily corroded. It really has great significance if its corrosion resistance could be improved while the rust layer on the surface is removed by the laser derusting technology. [ABSTRACT FROM AUTHOR]