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The effect of artificial ageing on the intergranular corrosion behavior of 7055 aluminum alloy were investigated by accelerated corrosion test, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and elemental mapping of X-ray energy dispersive spectra (EDS). The results show that when the alloy is aged at 120 ℃, the grain boundary precipitates (GBPs) are the preferential corrosion sites; however, when the alloy is aged at 400 ℃, the Al-matrix near the GBPs is the preferential corrosion site compared rather than the GBPs. According to the TEM and EDS results, when the alloy is aged at 120 ℃, extended ageing leads to the coarsening and discontinuous distribution of GBPs as well as increased Cu content in the GBPs. These factors result in the evolution of corrosion morphology from a typical intergranular corrosion morphology to pitting morphology. When the alloy is aged at 400 ℃, Cu element atoms will concentrate in the precipitates, especially in the GBPs, and the Al-matrix deplete Cu element. As such, the corrosion potential of GBPs becomes higher than the Al-matrix nearby, causing intergranular corrosion guided by the Al-matrix dissolution along the grain boundary.