Ultrafine CaCO3 powder was prepared by low temperature hydrothermal method.The effects of the synthetic parameter such as different starting materials and reaction temperature on the properties of the resultant products were studied.The products were characterized by X-ray diffraction（XRD）,Fourier transform infrared spectrum（FTIR）,transmission electron microscopy （TEM）,thermogravimetric analytical and differential scanning calorimetry（TGA-DSC）.The analytical results indicated that the hydrothermally-derived CaCO3 powders from Ca（OH）2 and Na2CO3 at 120℃ for 20 h,mainly consisted of cubic-like crystallites with the sizes ranging from 130 to 650nm.
