Abstract: The welding residual stress in welded joint of thick-walled 316LN stainless steel pipes was studied by finite element modeling, and the influence of lumped pass on simulation results was analyzed. At last, simulated results were verified by X-ray diffraction stress measurement. The results show that the simulated results were corresponded with measured results if initial stress of pipes was considered. The axial residual tensile stress is found near the cosmic weld beads and located at the region that below the last weld bead. The value of tensile residual stress is higher and its distribution region is larger. The lumped pass method had a great influence on the distribution and value of residual compressive stress rather than the residual tensile stress that distributed across the cosmic welds. Reasonable lumped pass model is suitable for welding residual stress simulation of large-scale welding structure for its efficiency and reliable accuracy.