ZnO plate, dominantly exposed polar high energy (0 0 0 1) plane, was used to load Cu to build Cu/ZnO plate model catalyst. The catalyst was reduced in different atmospheres and then evaluated for CO2 hydrogenation to methanol. X-ray diffraction, scanning electron microscopy, quasi in situ X-ray photoemission spectroscopy, in situ UV-Raman, and CO2 temperature programmed desorption characterizations have been carried out. The exploration results indicate that in situ tuning Cu nanoparticle (NP) morphology can be realized through varying reducing atmospheres. H-2 reduction induced the formation of small irregular spherical Cu NPs covered with large amount of migrated Zn, prompting CO2 conversion and methanol synthesis. However, CO reduction induced the generation of ellipsoidal Cu NPs with medium size and low amount of migrated Zn, leading to poor catalytic performance for CO2 hydrogenation. CO2 hydrogenation to methanol displays apparent Cu NP morphology dependency over the Cu-ZnO based catalysts.