Abstract: Friction stir welding butt test of 5083 aluminum alloy T-joint was carried out by adjusting the welding position of tool and adding pre-welding procedure. The metallographic structure of the cross section of the weld was observed, the tensile and bending of the joint were detected, and the fracture was detected by scanning electron microscopy. The results showed that the traditional welded T-joints were prone to crack at the root, which could be eliminated by adjusting the welding position and increasing the welding depth, but it also caused the root to deform slightly, which could be eliminated by adding a pre-welding procedure. The tensile strength, yield strength and elongation at fracture of joints increased by 32.5 \%, 32.1 \% and 71.4 \% respectively after "adjusting welding position + pre-welding". After process improvement, the bending degree of specimen after bending detection flattened, the size of fracture dimple increased, and the fracture mechanism developed to the direction of ductile fracture.