In consideration of the preparation of CdS/CdTe solar cell back contact layer, the band structure and the density of states of undoped and (Y, Gd) doped in ZnTe were caculated from the plane wave ultra soft pseudo potential method based on density functional theory and generalized gradient approximation. We acquired the system total energy and lattice parameter. As a result, the structural stability improve after doping, the lattice match between ZnTe and CdTe are better when Y doped. (Y, Gd) doped make the ZnTe semiconductor degeneration. Compared with Gd, the electronic effective mass of ZnTe doped with Y are lighter. The carrier concentration order of magnitude in different doping system are same. We analysed the influence on ZnTe used for back contact layer when doped with (Y, Gd).