The geometrical structures of pure ZnO and Co and Mn codoped 32-atom supercell of ZnO were optimized by using the ultra-soft pseudopotential method of total-energy plane wave based on the density functional theory. Band structure, density of states and optical properties were calculated and discussed in detail. The results revealed that the band gap of Co and Mn codoped ZnO are reduced and the absorption to ultraviolet visible light is obviously enhanced.