The porous TiO2/SiO2 and TiO2/Al/SiO2 nanostructures are successfully fabricated by anodic oxidation of titanium or titanium/aluminum thin films deposited on transparent SiO2 glass substrates with pulsed laser deposition (PLD) technique. The optically transparent titania films, with highly ordered and uniformly arrayed pores are characterized by field emission scanning electron microscope (FESEM). The influence of Al buffer layer on the optical absorption of the porous TiO2 thin films was investigated. The results show that without Al buffer layer the UV absorption peak of the porous TiO2 films was fixed at 270nm and the intensity of absorption peak was not modulated by the anodic potential. However, with an Al buffer layer, the UV absorption peak will shift to 293nm, and the intensity of absorption peak was not only modulated by anodic potential, but also sensitively influenced by the thickness of Al buffer layer. Moreover, the optical transition property of the two nanostructures at the absorption edge was analysed.