Abstract: With the initial welded joint and second (ropair welding) welded joint of the simulated welded part of 5A06 aluminum alloy as research objects, the influence of repair welding on the mechanical properties of the welded joint was studied by tensile test, fatigue test and fatigue fracture morphology observation. The results show that the repair welding decreased the mechanical properties of the welded joint, especially decreased the static strength and median fatigue strength significantly. The weld seam was the weak part of the welded joint in tensile strength and fatigue performance, and the repair welding gave rise to the coarse grains of the metal near weld seam.