In order to solve the problems on synthesizing carbonated hydroxyapatites (CHA) by the conventional heating precipitation method, such as long reaction and large particle size, poor crystallinity of CHA etc, the nanosized CHA particles have been synthesized by microwave heating method using phosphoric acid (H3PO4), calcium hydroxide (Ca(OH)2) and calcium carbonate (CaCO3 ) as starting materials in the present paper. The influences of power level and time of microwave irradiation on synthesis of CHA have been investigated. The X-ray diffraction (XRD) analysis has indicated that microwave heating will reduce CHA crystallization time and improve crystallinity of CHA. Scanning electron microscope (SEM) analysis has showed that CHA particles are of rod like morphology with about 60nm width and 200nm length respectively. Infrared spectroscopy (IR) analysis has confirmed the B-type CHA precipitate can be formed under microwave irradiation. The microwave irradiation plays an important role to promote the reaction and the synthesis of nanosized CHA particles.