Multi-porous titanium dioxide films were prepared on pure titanium plates by micro-arc oxidation and the films were characterized. Micro-arc oxidation tests were carried out at room temperature and 0.5 mol/L H3PO4 used as electrolyte. Voltage was controlled as potentiostatic mode (200-350 V). Porous titanium dioxide layers are formed under all voltages but the morphological difference is obvious. The distribution of micro-pore size increases with increasing of the voltage. XRD and XPS analysis indicate that the micro-arc oxidized films are mainly composed of TiO2 and TiP2O7. With increasing of the applied voltage, both the TiO2 crystalline phase and the P content increase. The incubation results of the samples in simulated body fluid (SBF) show that HA (hydroxyapatite) formation is mainly due to the TiP2O7 resolved into . The ions are adsorbed in the sample surface as nuclear sites. The P content of about 4at% in the sample surface can hasten the apatite formation