Abstract: Study on the structure change of overheated coppertype methanol catalyst was carried out using electron spectroscopy, Xray diffraction, physical and chemical absorption analysis method. The results showed that the particle size of the overheated catalyst increased, but the specific surface area and pore volume decreased. After industrial use, the grain size of the catalyst increased, and the surface area and pore volume decreased more than those of the overheated catalyst in lab. Overheated catalyst in laboratory experiments and industrial use showed same change in the trend on structure. Surface area and catalyst activity decreased with associated changes. Because the impact of impurities on catalysts was very small under the condition of fully purified gas, the structural changes of catalyst were main reason of affecting the catalyst activity and life.