Abstract: The homogenization of welding residual stress in butt joint of high strength steels is studied by means of finite element software. The results indicate that the peak stress in the all of the welded joints in the transverse and longitudinal tensile process will increase continuously on the basis of welding residual stress due to the insufficient plastic reserve of the base metal, and the stress growth rate in every region of the butt joint is different. Finally, the residual stress is not absolutely homogenized. Due to the cover passes with high plasticity and low yield ratio in the under-matching equal static ELCC joints locate in weld and surface of the near the seam base metal where distributed the peak value of welding residual stress, and share the tensile load, resulting in that the stress growth rate of the base metal zone near seam is slow, therefore, its homogenizing capacities of welding residual stress is better than that of the equal-matching joint. Considering the effect of welding residual stress, the static load failure of ELCC joint is more likely to occur in the base metal zone rather than welding zone, which is consistent with the original design goal. It is clear that the influence of welding residual stress can be neglected in the design of static load ELCC of under-matching butt joint.