Transmittance spectrum distribution of submicron aluminum-doped zinc oxide (AZO) is discussed. A layer of positive photoresist (PR) is spin coated on AZO thin film and PR mask pattern is acquired with two-beam holographic interference exposure of 325 nm laser. Then it is immersed into 0.5% HCl (mass fraction) water solution to form one-dimensional AZO gratings. The periods and heights of the gratings are adjusted independently from each other and vary between 780~1280 nm and 60~300 nm, respectively. Results show that specular transmittance of 400~900 nm decreases rapidly with grating periods increasing. Bidirectional transmittance distribution functions (BTDF) with normal incidence not only verify this result, but also confirm that diffuse transmittance in the angular range of 30°~80° increases accordingly. The larger the period is, the higher the peak of diffuse transmittance is, and the peak position angle decreases slightly, which is consistent with the law of diffraction angular change with periods obtained by grating equation.