When marine equipment is served in the seawater environment, it will suffer seawater immersion corrosion. In addition, due to the influence of seawater flow or welding, it will also be subjected to stress. The impact of stress-electrochemical corrosion coupling is much more complex than that of the individual action, resulting in the prominent corrosion damage of equipment under stress. In this paper, the influence of different pre-stresses on the corrosion behavior of Ni-Cr-Mo-V high-strength steel welded joints was explored by using a low-temperature seawater environment simulation test device, and the methods of seawater immersion weight loss test, four-point bending stress loading test and electrochemical experiment. The results show that with the increase of corrosion time, the unstable corrosion products gradually change to a more stable form, which affects the corrosion rate and corrosion kinetic properties of the material. The results of electrochemical impedance spectroscopy show that the charge transfer resistance of the welded joint is low, and its corrosion rate in seawater is faster. In addition, the application of stress significantly increases the corrosion tendency of welded joints, resulting in an accelerated corrosion rate. These findings are of great significance for optimizing the welding process of high-strength steel materials for marine equipment and improving the corrosion resistance of structures.