The work aims to prepare hydroxyapatite coating with high crystallinity and few flaws. Hydroxyapatite coatings were prepared on titanium alloy by plasma spraying under different power. Then, the hydroxyapatite coatings were treated by steam at different temperature. Morphology and crystalline structure of coatings were characterized by scanning electron microscope and X-ray diffraction. When the power of plasma spraying increased from 20 kW to 29 kW, the deposition efficiency of hydroxyapatite coatings increased at first and then tended to be stable, the crystallinity of hydroxyapatite coatings increased at first and then decreased and the content of calcium oxide in coatings increased at first and then tended to be stable. Crystallinity of hydroxyapatite was the highest when the power of plasma spraying was 23 kW. Steam treatment could obviously eliminate α-tricalcium phosphate, β-tricalcium phosphate and calcium oxide in coatings. As the temperature of steam treatment increased from 140 ℃ to 200 ℃, the crystalline grains of hydroxyapatite coatings changed from stick grains to granule grains. Crystallinity of hydroxyapatite coatings increased constantly and the content of tetracalcium phosphate in coatings decreased at first and then increased. Relatively high temperature resulted in occurrence of flaws. After soaking in simulated body fluid, the coatings after steam treatment could induce the deposition of pure hydroxyapatite. When the temperature of steam treatment was 180 ℃, there was a uniform layer of hydroxyapatite on the surface of coating, which indicated high creature activity. Crystallinity of hydroxyapatite coatings increases at first and then decreases as the plasma spraying power rises, but increases as the temperature of steam treatment rises. The hydroxyapatite coating prepared under appropriate conditions has relatively high creature activity.