The spraying-dried HA （ ASD ） was employed. ASD was plasma-sprayed onto ice to obtain hollow HA microspheres. The particle size of the sample was determined with a particle size analyzer. The morphology and structure of the samples were measured by scanning electron microscope and X-ray powder diffraction. The in vitro biodegradability of samples was evaluated by immersion tests in Ringer＇ s solution （RS） and simulated body fluid （SBF）. The samples were immersed respectively in RS and SBF for a period. The Ca^2＋ ion concentration in the solutions was determined by Atomic Adsorption Spectrum. By plasma spraying hollow HA microspheres were obtained. The hollow microspheres consisted mainly of low crystalline and amorphous HA, and had better biodegradability.
