Porous ceramic layer was deposited on pure titanium substrate by micro-arc oxidation(MAO). XRD and SEM were employed to characterize the phase composition and microstructure of the film. The effects of micro-arc oxidation time on microstructure and phase composition of TiO2 coating were analysed. The results show that, with the increase of oxidation time, the number of micro-pores decreases, while the size of micro-pores, roughness and thickness of MAO coating increase.MAO coating shows dentrites grew, but not traditionally nucleation and grow. Oxidation coating growth inward, while at the same time to growth outward. Grow into a dense ceramic membrane layer inward, outward growth into the porous layer. The coating is mainly composed of Ti, anatase and the rutile phases.