A process for hydrogenating carbon dioxide to generate methanol. In the process, a strip of copper base plate is transported by the groups of rotating drive rollers to deposit porous metallic zinc on the copper base plate. Hydrogen is generated from the porous metallic zinc upon electrochemical reactions in the inner space sealed with the above groups of rollers. Simultaneously, zinc oxide and copper oxide catalysts are formed on the porous metallic zinc. Carbon dioxide is introduced into the sealed inner space under high-temperature and high-pressure to generate methanol by hydrogenation.