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Mesoporous materials with tailored pore structures and high surface areas have many applications in the areas of adsorption and catalysis.Much attention has focused on the preparation of nanocrystalline semiconductors,especially TiO2,under milder conditions by using soft chemistry methods.The sol-gel method usually derived precipitates are amorphous in nature,and require further annealing treatment to induce crystallization.1-3 However,the photocatalytic activity of titania is dependent on both particles size and degree of crystallization.4 To the best of our knowledge,there is no report about synthesizing mesoporous TiO2 with photo-assisted MWI without template.Introducing UV illumination TiO2 colliod has at least three advantages than conventional MWI methods:i) UV illumination induces the formation of oxygen deficiencies in the titania nanoparticles and promotes the transition from amorphous to anatase phase at a lower temperature.ii) At the same time UV illumination induces the formation of Ti3+,which considered as doptants in the titania nanoparticles can reducing the combination of electron and hole pairs and thus promots the catalitic activity.iii) Due to the existence of Ti3+,which can declined the aggeragation activity of colloid,thus the structer of nanoparticles also can be improved.