<p>Sulfate saline soil distributes extensively in the cold and arid regions of Northwestern China, where its corrosivity poses serious risks to the service life and structural integrity of buried pipelines. To investigate the corrosion behavior of X80 steel in sulfate saline soil, electrochemical experiments, polarized optical microscopy, scanning electron microscopy, x-ray diffraction and x-ray photoelectron spectroscopy were conducted. The results indicate that the corrosion rate initially increases and then decreases with increasing salt content. The corrosion products show a porous and loose morphology, accompanied by local pitting corrosion at low salt contents. The corrosion layer structure becomes denser as the salt content increases. After the crystallization of mirabilite (Na₂SO₄·10H₂O), the corrosion layer structure becomes loose again since the liquid pore water content is reduced, and the contact area between the pore solution and the steel surface diminishes. For X80 steel exposed to saline soil with salt content below 2%, the corrosion rate displays a slight upward trend with corrosion time, whereas the corrosion rate shows a declining trend over corrosion time in saline soil with salt content exceeding 2%. These findings provide valuable references for corrosion analysis and protective design of pipeline steel in saline soil regions.</p>