The electronic structures and the optical response functions of In2O3 are were calculated by using a first-principles ultra-soft pseudo-potential approach of the plane wave based upon the density functional theory(DFT), and the relationships between the electronic structures and optical properties are were investigated. The dielectric functions, reflectance spectra, energy-loss function Im dominated by electron inter-band transitions are were analyzed in terms of the precisely calculated band structure and density of state. The properties of chemistry and physics are were studied by the difference charge density. The calculated results indicate that the optical transmittance of In2O3 is higher than 85% in the visible region, and can prepare transparent conductive Ooxide thin films can be prepared. Furthermore, the calculated conclusions offer theory theoretical data for the design and application of optoelectronics materials of In2O3, and also enable more precise monitoring and controlling during the growth of In2O3 materials as to be possible.

Key words: In₂O₃, optical propertiesy, electronic structure, the first-principle