Abstract: In order to study effect of incident angles on IR polarizing property of Co-Al2O3 film, Co was implanted into the pores of anodic alumina by means of electroplating. Its transmittance spectrum was measured with UV-3101PC spectral photometer, and its polarizing spectrum was tested at the incident angles of 30 and 45 respectively. The experimental result indicates that such anodic alumina film with Co columns has good transmittance and extinction ratio in the near-infrared waveband, and the extinction ratio improves notably with increase of the incident angle.