Abstract: A three-electrode electrochemistry method is adopted to research the corrosion resistance of heat-affected zone for X80 pipeline steel welding joint prepared by two welding wires(H06H1 and H05MnNiMo) in the Na₂S solution.The results show that the metallurgical structure of the weld heat-affected zone is needle-like ferrite and granular bainite, and the crystal grain is petty.The corrosion rate of the heat-affected zone increases as the raise of Na₂S concentration and temperature, which the corrosion speed is 0.240.81 mm/a when the temperature is 20-60℃ and the concentration of Na₂S is 1.0%-2.0%, and the corrosion procedure is the anodic polarization of corrosion system;the corrosion procedure is anodic diffusion when the temperature is above 40℃.