The　welding　residual　stress　of　lap　joints　of　thin　steel　sheets　was　measured　by　the　cos　alpha　X-ray　diffraction　method　and　compared　with　the　numerical　simulation.　The　longitudinal　residual　stress　in　the　region　near　the　weld　is　close　to　the　yield　strength　of　the　base　metal.　The　welding　residual　stress　distribution　is　asymmetrical　on　the　two　plates　and　two　sides　of　the　weld　because　of　the　asymmetrical　geometry　of　the　lap　joint.　A　higher　residual　stress　was　observed　on　the　lower　plate　of　lap　joints.　The　longitudinal　residual　stress　has　almost　the　uniform　distribution　along　the　weld　line　except　near　two　ends.　The　influencing　length　near　two　ends　of　the　weld　line　is　about　20-30　mm.　The　maximum　tensile　value　of　the　longitudinal　residual　stress　of　the　lap　joint　of　the　high　strength　steel　TS590　is　higher　than　that　of　the　mild　steel　TS270.　(C)　2016　Elsevier　B.V.　All　rights　reserved.