Due to the lack of the right outer wing part of the test piece, the many and complicated butt joint, and the large test load, which brings great difficulty to the application of the wing load. Therefore the independent loading clamp is designed for the three sets of joints. The actual load of the front and middle joint is reduced by extending loading force line spacing. According to the opposite loading position of the upper and lower joints, different loading joint connection forms are designed to ensure the deformation freedom of the actual butt joint of the aircraft. The rear joint load is adjusted by coordinate conversion, and the test site is conveniently implemented. The method can ensure to transmit the accurate load to the joint, avoid the rigidity matching problem between the joints, and is convenient to install and meet the test requirements. The use of local restraint device effectively avoids the generation of harmful damage at the joint and protects the joint in real time.