−To investigate the effect of precipitation on physico-chemical and catalytic properties of Cu-Zn-Al catalyst, the pH value and injection rate in the precipitation process were systematically changed, and the water-gas shift reaction was carried out. The Cu-Zn-Al catalyst showed the highest CO conversion when the optimized synthesis parameters (i.e., pH=10-10.5 and injection rate=30ml/min) were employed. This is mainly due to the enhanced physicochemical properties such as a high Brunauer-Emmett-Teller surface area, small crystallite size, high Cu dispersion, and easier reducibility.