Abstract: The friction stir welding of antirust aluminum alloy was investigated through series of experiments, and the metallographic structure and the mechanical properties of the joint were analyzed, and the effects of welding parameters on the structure and properties were discussed.For the 3 mm thick plate of antirust aluminum alloy, the optimal material of the pin is 1Cr18Ni9Ti, and the optimal shape is as follows: circular cone with concave surface, the diameters of the shoulder, the root and the tip are 12 mm, 4 mm and 2.8 mm, respectively, and the length of pin is 2.7 mm.The optimal welding parameter ranges are that the rotation speed is from 950 rpm to 1 500 rpm and the welding speed is from 37.5 mm/min to 60 mm/min.This research can be used in the friction stir welding of the other nonferrous materials, and also can promote the application of friction stir welding in welding of aluminum alloy.