To improve the adhesion and corrosion resistance of HA (hydroxyapatite) on implant alloy, electrolytic HA/ZrO2 double layers coating was conducted on Co-Cr-Mo alloy (ASTM F-1537) in zirconyl nitrate (ZrO (NO3)2) and subsequently in Ca(NO3)2°D4H2O + NH4H2PO4 aqueous solutions. By controlling the electrochemical parameters such as concentration, potential and time, the best deposited condition for HA/ZrO2 coating on Co-Cr-Mo alloys substrate has been investigated. After annealed, the HA coated and HA/ZrO2 coated specimens were further characterized by using XRD, SEM/EDS, polarization tests, ultrasonic vibration tests, scratch tests, immersion tests and cell culture. The HA/ZrO2 double layers coated specimens exhibited more corrosion resistant than the single layer HA coated or uncoated specimens for the cyclic tests in Hank°¦s solution. The HA/ZrO2 double layers coating revealed more adhesive than the single HA coating on Co-Cr-Mo alloy for both ultrasonic vibrating tests and scratch tests. HA reprecipitated on both HA and HA/ ZrO2 coated specimens for the immersion tests in Hank°¦s solution. The osteosarcoma proliferation on the HA/ZrO2 and HA coated specimens was more than that on the uncoated or the bi-phase calcium phosphate (£] tricalcium phosphate and HA) coated. The SEM observations cell culture showed the better and faster extension of osteoblast cells on HA/ZrO2 and HA coated than that on the uncoated. Conclusively, the adhesion and the corrosion resistance of HA on Co-Cr-Mo were enhanced by the interlayer coating of ZrO2. Also, the excellent bioactivity and osteoconduction of HA/ZrO2 coating remained as that of HA coating.