The Ag-doped TiO2、Ce-doped TiO2 and Ag-Ce co-doped anatase TiO2 systems are built by the substitution doping of Ag and Ce atoms at the anatase TiO2. The electronic structures and optical absorption properties of the doped systems are investigated with the first principle. The results show that, as for the Ag-Ce co-doped anatase TiO2, a shallow impurity energy level conducive to electronic transition is introduced with the synergy of Ag-4d and O-2p electron orbits; its forbidden bandgap is reduced because of the strong synergy of Ag-4d and Ce-4f electronic orbits, which results in the red shifts of the absorption spectra; the introduction of Ce ions effectively reduces the recombination rate of electron-hole pairs in the impurity system, which improves the quantum efficiency of the system. Therefore, the Ag-Ce co-doped anatase TiO2 not only extends the range of the absorption spectra but also increases the quantum efficiency of TiO2, and the photocatalytic property of TiO2 is improved.