A method for preparing titania or precursor thereof with a controllable structure from micropore to mesopore is provided. The method is characterized in that the alkali metal titanate as raw material is reacted for 0.5˜72 hours in the wet atmosphere with humidity of 2˜100% at temperature of 20˜250° C., then washed with water or acid, finally performed by air roasting or solvent thermal treatment. The method has advantages that the raw material is easy to be obtained, the conditions and preparation are controllable, the pore structure may be adjusted from micropore to mesopore, crystal mixing and doping are easy, reacting time is short, preparing cost is low, and the said method is suitable for large scale production and so on. The most probable aperture of titanium oxide or precursor thereof with a controllable structure from micropore to mesopore is in the range of 1˜20 nm, the pore volume thereof is in the range of 0.05˜0.4 cm3/g, and the specific surface area thereof is more than 30 m2/g. The titania is at least one of anatase-phase titania, TiO2(B)-phase titania and rutile-phase titania.