Abstract: To explore the influence of pitting corrosion on the fatigue performance of steel, this paper conducted finite element numerical simulations of pitting corrosion on Q235B steel, and established a finite element model of corroded steel with semi-ellipsoidal pits. The model was used to examine the effects of pit depth, width, stress amplitude and pit spacing on the fatigue performance of steel, and to develop the S-N curve of steel with corrosion pits. The results show that the depth of the corrosion pit is significantly negatively correlated with the fatigue life of the steel. As pit depth increases, the stress concentration area migrates toward the center of the corrosion pit. With increasing pit width, the fatigue life of the steel exhibits a logarithmic increase, and the stress concentration area shifts from the center of the pit to its edge. As the stress amplitude increases, the fatigue life of steel decreases logarithmically, with an accelerated rate of life attenuation. In contrast, the pit spacing has no significant effect on the fatigue life of steel. The research results can provide a theoretical basis and data support for fatigue design and service life evaluation of corroded steel structures.