Plasma-sprayed hydroxyapatite coating on metal substrate has been prepared, two kinds of post-treatment methods have been used: (1) Heating in air at 650°C for 30 min, (2) Heating in water vapor at 125°C, 0.15Mpa for 6 hours. XRD showed that the nanocrystals of HA coating increased after water vapor treated. The interfacial tensiles strength between HA and the substrate were 45.0±1.82MPa, 39.1±1.27MPa and 30.3±1.61MPa for as-received coatings, water vapor treated coatings and heated in air coatings respectively. After 3 months implant in dogs limbs, the push-out strength between implants and bone were 11.27±2.71 MPa, 11.63±3.11MPa, 23.92± 2.01MPa and 18.8±1.82 MPa for pure Ti implants, as-received coating implants, water vapor treated implants and heated in air implants respectively. The results showed that the water vapor post treated HA coating have better mechanical behavior in vitro and in vivo.