Abstract: Based on the ultra-soft pseudopotential approach of the plane-wave based upon density functional theory, the supercell of pure SnO2, SnO2:In, SnO2:Ga and SnO2:(In, Ga) model was established, its geometry structure was optimized, and the band structures, density of states, charge density and optical properties were obtained. The results show that the lattice constant of SnO2:(In, Ga) is more close to the pure SnO2, comparing with the SnO2:In and nO2:Ga, which can effectively reduce the lattice distortion of doped SnO2. The bandgap value increase and the band structure move toward the high energy direction for the doped SnO2, presenting p-type features. For the co-doped SnO2:(In,Ga), the electron clouds of the In (Ga) and O atoms have shown the characteristics of covalent bond. For the SnO2:(In, Ga), when the photon energy about 0~2.45eV and greater than 6.27eV, the crystal performance shows pretty dielectric character, which has a good application prospect in tiny microelectronic sensor mechanical system device and high density information storage. SnO2:(In, Ga) will be widely used in the photoelectric device for its strongly absorption capacity of light energy, the absorption coefficient reached to 105 cm-1.