The energy bands of La -doped ZnO were studied systematically by the density functional theory (DFT). Based on the data of the band structure, DOS (Density of State) and PDOS( Partial Density of States), atomic populations and net charge, the influence on the energy band structure of the macrostructure of ZnO and La-doped ZnO was investigated. The results showed that the free electrons were produced by the doping of La on (or in) ZnO crystal. The Fermi energy was shifted up to the conduction band, making the ZnO particles having the characters of degenerated semiconductor. The excitation from impurity states to the conduction band may account for the blue shift of the absorption edge in the model of La-doped ZnO. Comparison with the different models of the La doped/loaded on the ZnO surface, La atoms loaded on the surface of ZnO and La atoms replaced of Zn atoms on the ZnO surface, the shift to the lower energy location were found after La doping/loading. The more shift and the large band gap was found for the model of La doped on the Zn position in the ZnO crystal.