Cu/ZnO/Al2O3 ultrafine catalysts have been prepared by a novel oxalate gel coprecipitation method. The effect of the post-condition on the structure, surface properties of the catalysts and their precursors as well as the catalytic activities for methanol synthesis from CO/CO2 hydrogenation have been studied. The results showed that the washing with ethanol or drying directly derived a large specific surface area, highly dispersion ultrafine Cu/ZnO/Al2O3 catalysts, which exhibited a higher catalytic activity and optimum methanol selectivity for methanol synthesis from CO/CO2 hydrogenation. The reaction route and mechanism of methanol formation were also discussed.