HA was coated onto the surface of alumina substrate, with a view to overcome the poor mechanical properties of HA and the biocompatibility of alumina. Improvement was attempted by adding a bond coat of porcelain via plasma-spraying and by post heat-treatment. The results showed that the bonding strength of as-sprayed P0 (without bond coat), P50 (with HA/50wt% porcelain bond coat) and P100 (with 100wt% porcelain bond coat) samples were all nearly 13 MPa. The bonding strength of post-heat-treated P0 at 900°C was found to increase by 5 MPa. And, the bonding strength of post-heat-treated P50 and P100 at 850°C increased by 8 MPa. Besides, post-heat-treatment at 850¡æ achieved the maximum bonding strength for P50 and P100 samples. Investigating the coating morphologies showed that the surface roughness of HA coatings with bond coat increased as compared with coating without bond coat, and the surface roughness of former HA coatings decreased after heat-treatment. By EPMA element analysis, it was found that at interface of HA and porcelain, calcium diffused from HA into porcelain, which apparently enhance the bonding of the interface. The failure mode showed that P0 sample in as-sprayed and post-heat-treatment at 750°C and 800°C fractured along lamellar splats of HA and at interface of HA and Al₂O₃ substrate. And, the post-heat-treated P0 at 850°C and 900°C primarily fractured along the interface of HA and Al₂O₃ substrate. However, P50 and P100 samples in as-sprayed and post-heat-treatment at 750°C were fractured along lamellar splats of HA and at interface of bond coat and Al₂O₃ substrate. After heat treatment at 800, 850 and 900°C, fracture of the tensile test occurred primarily along the lamellar splats of HA and the inside of bond coat.