Abstract: This study investigates the degradation mechanisms of fatigue performance and the evaluation methods of fatigue performance of EH690 high-strength steel welded joints after corrosion. Taking 16 mm thick EH690 steel as the research object, 16 butt joint specimens were prepared by gas metal-arc welding (GMAW), and accelerated corrosion was conducted by salt spray test with corrosion durations of 240, 480, 960, and 1920 h, and the corrosion degree was measured by the mass loss method, and the corrosion notch parameters at the weld toe and the microstructural morphology characteristics after corrosion were characterized by means of a three-dimensional scanning system and an optical microscopy system, and constant amplitude sinusoidal loading tests were completed on a fatigue testing machine. The results show that as the corrosion time prolongs, the corrosion notch at the weld toe deepens, the notch radius decreases, and the stress concentration factor exhibits an increasing trend, leading to a significant reduction in the fatigue life of the welded joints; based on the experimental data, a stress amplitude correction method for EH690 steel welded joints after corrosion is proposed, and a model relating the geometric parameters of the corrosion morphology to the stress concentration factor is established, which can provide theoretical reference for the anti-fatigue design and life prediction of EH690 steel welded structures.