Abstract: The corrosion behavior of a friction stir welded2219 aluminum alloy was investigated using both normalized intergranular corrosion test and exfoliation corrosion test. The surface morphologies and the compositions of the corrosion products were analyzed by optical microscopy(OM), scanning electron microscopy(SEM) and energy disperse spectroscopy. A preliminary discussion was carried out on the corrosion mechanisms of FSW joint. The results show that the general corrosion behavior of the weld is superior to that of the base metal and that of WNZ is the best. Corrosion begins from pitting corrosion, and gradually develops to intergranular corrosion and exfoliation corrosion.When the corrosion happens, the homogeneous composition increases the corrosion potential, then the corrosion resistance increases.