The residual sodium in the Cu/ZnO/ZrO2 catalyst is found to inhibit the interaction between CuO and ZnO and lead to a decrease in the catalytic activity for CO hydrogenation. Therefore, it is required to reduce the content of sodium as much as possible during the course of catalyst preparation. To obtain 10% yield of methanol, the sodium content must be reduced to a level lower than 0.15%. For this purpose, the washing condition has been investigated experimentally to optimize the preparation conditions of Cu/ZnO/ZrO2 catalyst. As a result, the sodium content could be reduced to 0.115% by washing the cake four times with 50 mL of distilled water per gram of the cake, which constitutes the optimum condition for washing.