Objective This study was undertaken to examine the material characteristics of BG-nHA gradient coatings and the bonding behaviour of the interface between the BG-nHA gradient coating and titanium alloy (Ti-6Al-4V) substrate. Methods The BG-nHA gradient coatings were prepared on the titanium alloy by using hypothermy sintering technology and the characteristics of coatings were evaluated by SEM、EDS、XRD and FITR. The bonding strength between the gradient coatings and the alloy substrate was tested according to ISO 13779-4:2002 before and after immersion in Tris- HCL buffer solution. The mass loss of the gradient coating and the ion released were determined. Results The results showed that the gradient coatings were porous and its surface were composed of rod-like nano-HA crystals. The interface between the coating and titanium alloy was dense and no cracks were found at the interface. The bond strength between coating and Ti-6Al-4V was 39.7±4.4Mpa. The mass loss and released ion increased gradually when immersed in Tris-HCL buffer solution. Conclusion The BG-nHA gradient coatings can be prepared by the hypothermy sintering technology and the bioactive glass reinforced nano-HA coatings have high bond strength to titanium alloy substrate.