In　order　to　take　into　account　the　change　of　stress　and　deformation　during　the　whole　process　of　welding　and　the　thermal　field　distribution　of　a　U-rib　stiffened　plate,　a　thermal　elastic-plastic　FEM　model　was　adopted　and　element　birth　and　death　was　used　to　simulate　the　weld　seam　fill-in　and　heat　input.　And　the　residual　stress　distribution　was　investigated　by　numerical　simulations　and　experiments.　The　comparison　of　numerical　analyses　and　experimental　results　of　distribution　and　magnitude　of　residual　stress　showed　that　residual　stress　near　the　weld　seam　is　close　to　material　yielding　stress,　the　average　value　of　the　residual　stress　far　from　weld　seam　on　the　mother　board　was　around　0.2　time　of　material　yielding　stress.　The　residual　stress　distribution　tendency　derived　from　numerical　simulation　was　close　to　the　experiment　result,　which　proved　the　validity　of　the　numerical　simulation.