Abstract: The stress state is the key factor for the fitness-for-service assessment of girth weld, and the misalignment causes the discontinuity of girth-welded structure, which changes the stress state of girth weld. In order to explore the mechanical behavior and stress distribution of girth weld with misalignment under the action of external load, the stress concentration of girth weld with misalignment was studied through wide plate tensile test, and verified by establishing a finite element model. Additionally, comparison was made with the calculated values obtained with the recommended method specified in BS 7910-2013 Guide to methods for assessing the acceptability of flaws in metallic structures and GB/T 19624-2014 Safety assessment for in-service pressure vessels containing defects. The research shows that misalignment can lead to obvious stress concentration in weld, the stress concentration coefficient calculated according to BS 7910-2013 is moderately conservative compared with the results obtained through the wide plate tensile test and finite element simulation, and for defect fitness-for-service assessment of girth weld of pipe with misalignment, equivalent stress concentration treatment of misalignment according to BS 7910-2013 is recommended.