Equal channel angular extrusion (ECAE) experiments were conducted on as-cast pure Cu, Cu–10%Zn, and Cu–30%Zn, using a 90 die for up to 4 passes. The stacking fault energies (SFEs) of the three materials decrease with increasing Zn content. The microstructures and textures of the processed billets were analyzed using optical microscope and X-ray diffraction, respectively. The results show that the structures of the three materials were all significantly refined after ECAE and a lower SFE led to a finer microstructure with a higher density of shear bands. The textures were considerably weakened after 4 passes, more apparent in the material with a lower SFE. It is concluded that the SFE has significant influences on both the grain refinement and texture evolution during ECAE deformation.