In this work, the effects of concentration and mixture ratio of Ca(CH3COO)2•H2O and Na5P3O10 in electrolyte on surface morphology, surface content and atomic ratio of calcium and phosphorus elements, and phase structure of ceramic coating prepared by micro-arc oxidation（MAO）on TC4 titanium alloy were studied, a suitable formula of electrolyte for bio-modification of titanium by MAO was obtained, Ca(CH3COO)2•H2O 20 g/L and Na5P3O10 9.3 g/L. Using this electrolyte with appropriate process conditions, the ceramic coating was prepared with porosity structure and combines well with the substrate. The pores distributed equably on the surface of ceramic coating and the size of the pores was in micron order. The surface of the ceramic coating contains calcium, phosphorus elements and their atom ratio is about 1.69 which nears to that of hydroxyapatite. The ceramic coating was composed of titanium dioxide in different crystal types which have been characterized by the X-ray diffraction (XRD). The anatase titanium dioxide was a major component.