Abstract: The electronic work functions of MnS, Al₂O₃, SiO₂, Cr₂₃C₆, σ, Laves, Cr₂N and multiple crystal planes of the steel matrix were calculated and compared using the first principles of density functional theory (DFT). The mechanism of pitting induced by different inclusions and precipitates with different crystal planes and different terminal planes of the same crystal plane was analyzed. In addition, the adsorption process of sulfur and chlorine on steel matrix in sulfur and chlorine corrosion medium was simulated, so as to analyze the corrosion resistance difference and electronic cause of 254SMO in sulfur and chlorine corrosion medium.