Abstract: Objective The actual strength matching state of girth welded joints in long-distance pipeline is complex and variable, and local strain concentration behavior of welded joints with different strength matching states during loading and performance deterioration caused by subsequent strain aging has an important impact on its service safety. Methods In this paper, strain concentration of under-matched, even-matched and over-matched girth welded joints during full wall thickness tensile test is quantitatively characterized by digital image correlation technology (DIC). Influence of different strength matching coefficients of root welding, filling and covering welding on local strain concentration behavior of girth welded joints is analyzed by ABAQUS. Moreover, effect of strain aging on toughness of root micro-zone in girth welded joints is further analyzed. Results The experiment results show that when remote strain of pipe body is 0.5%, except over-matched welded joints, root welded zone of girth welded joints show notable local strain concentration during the tensile process for under-matched state and even-matched state, and root strain concentration can reach 7.55% and 4.67%. The simulation results show that root strain concentration of under-matched joints reach 7.56%, and root strain concentration decreases with the increase of matching coefficient. After strain aging, toughness of root micro-zone of under-matched and even-matched girth welded joints decreases significantly, with a decrease of 42.6%～52.1%, while toughness reduction of over-matched girth welded joints is very little. Conclusion Girth weld of high-strength steel pipelines adopts an overall over-matching design, and root welding position should also adopt even-matching or over-matching, which effectively enhances strain resistance of girth welded joints, thereby improving service safety of pipelines.