The Al-doped ZnO (AZO) films with different Al doping concentrations are fabricated on the Al2O3 substrates. The effects of Al composition on the photoelectric and surface plasma properties of AZO films are analyzed by the ultraviolet-visible (UV-Vis) absorption spectra, Hall measurement, refractive index and dielectric constant measurements. With the increase of Al composition concentration, the absorption edge is blue-shifted and the absorption intensity decreases gradually ,which means the optical loss is reduced. Meanwhile, the carrier concentration and mobility first increase and then decrease, while the electrical loss first decreases and then increases.