Abstract: To study the distribution characteristics of welding residual stresses in high strength flat-bar stiffened plates, stresses in flat-bar stiffened plates were measured with the method of sectioning technique. 3-D solid thermal elastic plastic finite element method (FEM) was developed by using element birth-and-death method and dynamic constraints technique to simulate the process of weld filler variation and welding heat input. Residual stress distribution between high strength steel and common strength steel was analyzed, while the effects of flange thickness, rib thickness, rib space and height on welding residual stresses were studied comparatively. The results show that welding sequence in T joint of flat-bar stiffened plates is irrelevant to stress distribution. Longitudinal compressive residual stresses out of weld zone of high strength steel are less than those of common strength steel. Plate thickness and wed height are the main factors affecting welding residual stresses in high strength flat-bar stiffened plates.