The titania film was formed by micro -arc oxidation on titanium alloys.The microstructure and chemical composition were studied by SEM,XRD.At the same time ,the hardness,elastic modulus and scratch resista nce measurement were carried out as well by nano -indentation and scratch machine.The results show that the micro -arc oxidation film which is consisted of cry stal and little amorphous phase has nano structure .The hardness and elastic modulus are 0.76GPa and 34.6GPa respectively.There is no film destroyed unless under high load.