A unidirectional porous glass structure coated with a nanometer TiO2 thin film on pore walls was successfully fabricated by a two-step process. Firstly, a water-based slurry of sheet glass was frozen while controlling the growth direction of ice crystals, and then sublimation of the ice under vacuum formed the green body. The green body was subsequently sintered to produce porous glass with unidirectional pores. Secondly, the sintered porous glass was infiltrated by a titanium (IV) butoxide solution, and then dried and calcined at a moderate temperature to generate a nanometer TiO2 film on pore walls. The present porous glass with nanometer TiO2 has more total surface area than the TiO2 film on glass plates, which is believed to be more effective in the phtotocatalysis application for air or water purification.