In order to analysis the corrosion mechanical property of steel strands under the coupling effects of chloride ion and variable load， the corrosion process of the steel strands by the accelerated corrosion test was simulated. Grayscale was used to quantify the corrosion degree of steel strands in different stress amplitudes and the failure mode and the fatigue of steel strands were also analyzed. The results indicate that greater amplitude of the stress applied at both ends of the strands will lead to more severe corrosion of the strand， and the single fatigue source failure is prone to occur. While smaller stress amplitude will result in slower corrosion speed， and the fracture of multiple fatigue sources and delamination is prone to occur. The relationship between tensile strength and corrosion rate is exponential， and the relationship between elongation and corrosion rate is linear attenuation trend； the increase of corrosion degree has a significant effect on the fatigue life of steel strands.