The electronic structures and optical properties of intrinsic, Co, Mo doped and Co-Mo codoped Al2O3 compounds are calculated by using first-principles plane-wave ultrasoft pseudopotential method based on the density functional theory. The results show that the binding energies of Mo single doping and Co-Mo co-doped Al2O3 are low and easy to synthesize. Both Co and Mo dopings belong to the n-type doping, which can enhance the carrier concentration of the doping system, and thus improving the conductivity of Al2O3. The impurity levels of the doped system are mainly composed of co-3d state electron and mo-4d state electron，which are the intrinsic factors that affect the optical properties of doped Al2O3. After doping, the absorption spectrum is redshifted and the optical properties change mainly in a low energy range. The transmittance of the Al2O3 film in the range of 200~800 nm is about 92%. The transmittances of the Al2O3 doped by Mo single and co-doped by Co-Mo are as high as 93~98% in the band of 600~780 nm. In the short-wave ultraviolet region of 200~280 nm, the transmittance of Co single doping can be as high as 95%. Therefore, three doped Al2O3 can be used to prepare various optical transmission films.
