With chemical coprecipitation method, high purity hydroxyapatite was successfully prepared in this paper. The microstructure and components of HA were characterized by XRD, SEM, FTIR, atomic emission spectrum and particle size analyzer. The results demonstrate that synthesized HA is very pure and is harmless to human body. Average particle size of HA powder is about 10.4μm. Crystallization degree of hydroxyapatite increases with the increase of sintering temperature and the optimal preparing technique is sintering at 750 for 2h with temperature-rising rate of 5°C·min-1. Grain growing activation energy of HA can be calculated as 24.8 kJ·mol-1 according to the relationship between grain size and sintering temperature. HA’s grain growth mechanism is interfacial diffusion controlling mechanism.