Calcium carbonate (CaCO 3 ) particles with various shapes were prepared by the reaction of sodium carbonate with calcium chloride in the presence of a new functional double-hydrophilic block copolymer poly (acrylic acid)-block-(acrylic hydroxy lactide) (PAAL) at room temperature. The as-prepared products were characterized with scanning electron microscopy and X-ray diffraction. The effects of pH, concentration of PAAL and CaCO 3 on the crystal form and morphologies of the as-prepared CaCO 3 were investigated. The results show that pH, concentration of PAAL and CaCO 3 are important parameters for the control of morphologies of CaCO 3 . Depending on the experimental conditions, various morphologies of CaCO 3 , such as plate-like aggregates, poly-nucleated spheres, ellipsoids, monodispersed spheres, rhombohedras, etc., can be obtained. Especially, the optimal experimental conditions for the production of monodispersed spherical CaCO 3 particles were determined.