A novel and facile synthesis route to large-pore mesoporous nanocrystalline anatase thin films with tunable pore diameters in narrow distribution of sizes ranging from 8.3 to 14 nm is reported, using triblock copolymer as the template and Ti(OBun)(4) as the inorganic precursor. The obtained materials were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and nitrogen adsorption. A reasonable formation mechanism is also presented in this work.