The TiO2/Al2O3 composite coatings were successfully prepared on the surface of Ti-6Al-4V alloy by means of micro-arc oxidation in the Na2SiO3-(NaPO3)6-NaAlO2 solution. Its growth process revealed that O2- reacted rapidly with Ti4 (from substrate) along the reaction channels to form TiO2, and because of the addition of AlO2-, Al2O3 and Al2TiO5 were simultaneously formed. Al2TiO5 was immediately decomposed into rutile TiO2 and α-Al2O3 owing to the high thermal energy caused by discharge. Finally the prepared composite phase coatings were mainly composed of anatase TiO2, rutile TiO2 and α-Al2O3 via XRD analysis. Furthermore, the wear resistance of the TiO2/Al2O3 composite coatings enhanced about 9.5 times than that of Ti-6Al-4V alloy owing to the existence of ceramic layer.