Abstract: Objective The aim is to explore influence of weld overlap on microstructure and mechanical properties of 6XXX aluminum alloy welded joints. Methods Referring to actual working conditions, two types of aluminum alloy welded joints with weld overlap were selected, and microstructure and mechanical properties were studied through metallographic examination, hardness testing, and tensile testing. Results The results showed that weld overlap had a minor impact on microstructure of welded joints. Evolution of solid solution zone could be determined by observing macrostructure, but specific effects of secondary solid solution and secondary overaging could not be determined by observing microstructure. The overall impact of weld overlap on mechanical properties of welded joints was positive. Butt weld underwent solid solution strengthening due to thermal effect of fillet weld, resulting in an increase in hardness. Tensile strength and elongation after fracture of weld overlap joints were higher than those of conventional butt joints. Conclusion Weld overlap does not affect normal use of 6XXX aluminum alloy welded joints.