The mechanical activation of CaHPO4.2H2O - CaCO3 with Ca/P ratio of 2.00 was carried out for 24 hours in planetary ball mill using agate vial and balls. Soaking ceramics in simulated body fluid (SBF) was used to evaluate the in-vitro bioactivity property. The resulting materials were characterizea by X-ray diffraction (XRD), Fourier Transformed Infrared Spectroscopy (FTIR), elemental analysis (CHN), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM), respectively. Results showed that complete transformation to pure nanocrystalline carbonatesubstituted hydroxyapatite (CHAp) with good bioactivity property could be obtained. Consequently, the high efficiency of this process opens a way to produce commercial amount of nanocrystalline CHAp powder is promising for fabrication of bone - resembling implants.