We report on the structural and optical properties of self-ordered nanoporous anodic alumina (NAA) films fabricated by hard anodization in different time. The morphology of NAA films is examined by scanning electron microscopy (SEM). The results show that the porous structure have hexagonally ordered arrays of nanopores with interpore distance about 260 nm and pore size 60 nm. The optical transmission spectra of the NAA films with different thickness are measured in the wavelength range of 800–900 nm. Base on SEM and optical transmission spectra measurements, effective optical thickness was evaluated and compared.