In this work, nano-TiO2 powders were deposited onto Ti-6Al-4V substrates to produce coating using plasma spraying. The TiO2 coatings were respectively by acid, alkali and heat treatment to produce the bioactive surface. The bioactivity of TiO2 coating was examined by simulated body fluids test. The results obtained indicated apatite was formed on the surfaces of nano-TiO2 coatings treated by H2SO4, HCl and HF solutions, while it could not be formed on the surface of the nano-TiO2 coating treated by NaOH solution at low concentration. After alkali attack and heat treatment at 600°C, the bioactivity of nano-TiO2 coating disappeared.