Abstract: Ultra-thin plate-shaped calcium carbonate with high radius-thickness ratio （more than 10∶1） was synthesized by adding crystal control agent and controlling technical conditions.Effects of various factors,such as reaction temperature,mass concentration of lime slurry,flow rate of CO<SUB>2</SUB> as well as adding amount and time of crystal control agent on the morphology of plate-shaped calcium carbonate were investigated.Optimum reaction conditions with oxalic acid as crystal control agent were obtained as follows:55~65 g/L of mass concentration of lime slurry,about 10.0 mL/min of CO<SUB>2</SUB> flow rate,and 20 ℃ of reaction temperature.