TiO6 octahedron structure is the basic framework of CaCu3Ti4O12 (CCTO), which associates with performance of optical and electronic properties, the investigation of dielectric and optical properties under various frequency region contribute to reveal origin of high dielectric constant. In order to explore the contributions of TiO6 octahedron to optical and electronic properties under various frequency region and the impacts of titanium and oxygen element, the model of ideal CCTO bulk, CCTO with oxygen vacancy and titanium vacancy are established, the structure, electronic density distribution and optical properties of three models are calculated and analyzed by plane-wave pseudo-potential method of first-principle calculation based on density functional theory. The calculated results show that oxygen vacancy and titanium vacancy have significant influences on structure and electronic density distribution, moreover, the optical properties such as refractive index, reflectivity, absorbance, and optical conductivity are deduced from the calculated dielectric function of three models above, and oxygen vacancy affect anisotropic of CCTO optical properties crucially.