Carbonated hydroxyapatite (CHA) was synthesized by solid-ion-exchange reaction of hydroxyapatite (HA) powders in CO2 atmosphere. The effects of the treatment atmosphere, temperature and time on carbonate substitution were investigated. The phase composition of the powders were characterized by X-ray diffraction and the content and type of the carbonate substitution were studied using Carbon-sulfur elemental analysis and Fourier transform infrared spectroscopy, respectively. The results show that the carbonate ion can enter the HA crystal lattice to form CHA giving priority to A-type by controlling the treatment temperature, atmosphere and time. Wet atmosphere treatment favors the reconstitution of hydroxyl and treatment in dry CO2 atmosphere favors the formation of A-Type substitution. The appropriate reaction temperature is 900 . Carbonate content increases with the treatment time and a further extension of treatment time tends to a slower increase of carbonate content.