Abstract: 5083-H321 aluminum alloy was welded by friction stir welding in the way of lap, and then the influence of the welding speed of on the tensile-shear strength and hardness of welded joint was studied. The results show that the tensile-shear strength of the welded joint could achieve above 200 MPa when the rotating speed of stirrer was 1 800 r·min and welding speed was 60 mm·min-1, the grains in weld seam of frist welding grew up due to the heat input of the second welding, which decreased tensile-shear strength and hardness.