In this paper we report recrystallization characterizations, using electron back-scattered diffraction (EBSD) and transmission electron microscope (TEM), of an Al-Zn-Mg-Cu-Zr alloy during multi-pass plain strain compression (PSC) performed to simulate the hot rolling system on Gleeble-l500D thermo-mechanical simulator．The results show that with increase of the deformation, there are mainly two dynamic recrystallization mechanisms responsible for the development of new grain, including continuous dynamic recrystallization (CDRX) and geometry dynamic recrystallization (GDRX). The former is related to original grain boundaries bulging and sub-grain coalescence. The latter can be associated with serious deformation inhomogeneity. Besides, SRX happens during inter-pass time. The particles with a size of more than 1 μm also result in the recrystallization.