The systematic trends and effect introduced by Zr and C co-doping to TiO2 of electronic structure and optical properties of anatase TiO2 have been calculated by the plane-wave ultra-soft pseudopotential density functional theory (DFT) method within the generalized gradient approximation (GGA) for the exchange-correlation potential. Through the current calculations, the density of states (DOS), energy band structure and optical absorption coefficients have been obtained for TiO2 and compared with the doped TiO2, and the influence of electronic structure and optical properties caused by Zr and C co-doping has been presented qualitatively together. The results revealed that the energy band gap has been decreased owing to the doped Zr and C, whereas the optical absorption coefficients have been increased in the region of 400～800 nm and a red shift of absorption band can be found. Accordingly, photo catalytic activity of TiO2 has been enhanced. The current calculations are in good agreement with the experimental data. The systematic trends and effect introduced by Zr and C co-doping to TiO2 of electronic structure and optical properties of anatase TiO2 have been calculated by the plane-wave ultra-soft pseudopotential density functional theory (DFT) method within the generalized gradient approximation (GGA Through the current calculations, the density of states (DOS), energy band structure and optical absorption coefficient have been obtained for TiO2 and compared with the doped TiO2, and the influence of electronic structure and optical properties caused by by Zr and C co-doping has been qualitatively together. The results revealed that the energy band gap has been reduced due to the doped Zr and C, whereas the optical absorption coefficients have been increased in the region of 400-800 nm and a red shift of absorption band can be found. It, photo catalytic activity of TiO2 has been enhanced. The current calculations are in good agreeme nt with the experimental data.