The structure optimization, band structure, density of states and light absorption characteristics of Zn-doped anatase TiO₂ are studied with the first-principles calculation method based on density functional theory(DFT). The calculations results show that Zn-doped anatase TiO₂ is indirect band gap semiconductor, and the impurity energy level is introduced due to the couping between O-2p and Zn-3d, which can increase the TiO₂ absorption edge to the visible region, and therefore enlarge the absorption region of TiO₂. The experimental results show that Zn-doped TiO₂ leads to the red shift of the optical absorption edges to visible-light region and enhance thephotoelectric effect of anatase TiO₂. The effect is useful for the photocathode protection of photoelectric performance.