Abstract: Although traditional chemical blackening process is widely used for corrosion protection on metal surfaces, it poses environmental pollution issues. A novel technique was proposed for in-situ formation of a continuous black Fe₃O₄ oxide film on steel surfaces using nanosecond pulse laser irradiation in an oxygen environment, and the relationship between film quality and laser parameters was evaluated. The research indicates that the thickness of the oxide film on steel surfaces increases with the increase in laser energy density and scan times but decreases with the increase in scanning speed, with the film thickness adjustable within the range of 1 to 12 μm. Despite the presence of mud cracks in the laser-blackened film, this defect does not significantly reduce the corrosion resistance and adhesion strength to the substrate. Electrochemical test results demonstrate a significant enhancement in corrosion resistance of steel with laser cleaning in oxygen environment, comparable to traditional chemical blackening. Salt spray tests further confirm that a film thickness in the range of 4.4 to 7.5 μm provides optimal corrosion resistance. Moreover, point defects in the oxide layer are identified as crucial factors affecting corrosion resistance. Therefore, precise control of laser processing parameters is crucial to ensure the quality and corrosion resistance of the oxide film. The findings of this study provide important guidance for optimizing future laser processes, showcasing the potential of laser technology in preparing high-performance anti-corrosion surface coatings.