Abstract: In order to study the relationship between ultrasonic processing milk of lime and purification efficiency, the morphology, specific surface area and chord length distribution of CaCO3 were characterized by means of scanning electron microscopy, surface area and pore size analyzer and focused beam reflectance measurement (FBRM) .Moreover, the color and turbidity of purified juice were determined.The results showed that calcium carbonate which generated from ultrasonic processing milk of lime had smaller particle size, larger specific surface area and purified juice had lower color and turbidity.Within an appropriate power range, processing milk of lime by ultrasound was an effective means of improving purification efficiency.