The　viewpoint　of　local　strain　was　applied　to　a　transverse　welded　wide　plate　with　a　crack　in　the　weld　metal.　It　can　be　shown　that　difference　in　the　plastic　properties　of　the　weld　metal　and　base　material　significantly　affects　both　fracture　toughness　and　crack　driving　force.　An　important　conclusion　is　that　showing　the　influence　of　mis-match　weld　joint　only　individually　according　to　toughness　or　crack　driving　force　is　not　sufficient　for　the　assessment　of　structure　integrity.　Moreover,　if　the　stress-strain-curve　of　base　material　and　weld　metal　can　be　expressed　as　the　linear　train-hardening　laws,　a　simplified　CTOD　design　curve　in　revised　formula　may　be　obtained,　which　can　serve　for　predicting　critical　loads,　critical　strains　or　critical　crack　length　for　the　welded　structures.