Density functional theory calculations were conducted to investigate the electronic structures of rutile Ti 16 O 32 , Ti 13 Nb 2 InO 32 , and Ti 13 Nb 2 InO 31 systems. High density (Nb + In) co-doped rutile TiO 2 ceramics were successfully prepared by one modified solid state method. XRD, XPS, Raman scattering and FT-IR measurements were performed to investigate the structural properties of the (Nb + In) co-doped rutile TiO 2 ceramics annealed in different atmospheres. The lattice parameters for the (Nb + In) co-doped rutile TiO 2 ceramics were enlarged slightly after they were annealed in air and oxygen. Raman scattering results indicate that the E g modes are quite sensitive to oxygen vacancy in comparison with the other Raman active modes. The ceramics annealed in oxygen at 873 K exhibit the best dielectric performance with giant dielectric permittivity (>14000) and small dielectric loss (<0.2) over the frequency range from 40 Hz to 1 MHz.