A series of CuZn catalysts with different pH values and molar ratios of Cu to Zn were prepared and tested for the CO hydrogenation to ethanol at low temperature in liquid phase. The results showed that the pH value and molar ratio of Cu to Zn of CuZn catalysts greatly affected the structure and CO adsorption properties. Catalytic performance had a direct relation with CO adsorption. The catalytic activity was determined by the total amount of CO adsorption over the catalyst surface, the weak CO adsorption accounted for the methanol synthesis, while the strong CO adsorption accounted for the ethanol synthesis. A reaction mechanism was also proposed.