A one-step anodization process was used to prepare the anodic alumina (AA) film on glass. Using the AA as an inserted underlayer, iron films with thickness of tN in the range of 10 ∼ 35 nm were deposited by argon ion sputtering. The iron film deposited on AA underlayer exhibited different magnetic behaviors from the iron film deposited on glass or on aluminum underlayer. The perpendicular coercivity of film deposited on AA underlayer reached a maximal value of about 1 kOe at tN = 30 nm. We believe that the improvement of magnetic properties came from the modulation of the morphology of Fe film by the porous structure of AA underlayer.