TIG welding was used to obtain 6061 aluminum alloy butt welded joints with good weld quality, and static tensile tests were carried out; The test results show that most of the samples are fractured in the softening zone 7~9 mm away from the edge of the weld fusion line. The mechanical properties and loss parameters of each micro-region of the welded joint are obtained by combining the double-hole microshear test with finite element, which is provided to the finite element calculation, and the finite element model of the static tensile test is established, and the correctness of the model is verified by comparison with the actual test results, on this basis, the influence of the relative width of the high-matching and low-matching welded joints and specimens on the failure behavior of the welded joints is studied, and the results show that for low-matching welded joints, the narrower the joint, the easier it is to fail, so the wider welded joints should be selected as much as possible; For high-matching welded joints, the narrower the joint, the less likely it is to fail, so it is recommended that narrower welded joints should be selected as much as possible.