The effect of CO on methanol synthesis from CO2 hydrogenation over Cu-Zn-Al cat-alysts have been investigated by TPSR-MS techniques and evaluated by testing the catalytic per-formance. The results indicated that CO can Occupy part of CO2 adsorption site on the catalystsurface to restrain the reverse water gas shift reaction and promote methanol synthesis in CO2hydrogenation . Therefore it inereases the Inethanol selectivity and yield from CO2 hydrogenation.