Abstract: The electronic structure of Cu_(n)Au_(m)(n+m=4) crystalloid clusters were calculated using density functional theory method of the first principles.It is shown that calculated crystal lattice parameters are in accord with the values of experiment.Based on the study on band structure and density of states(DOS),an argument that the d orbit electrons contribute to the energy levels is mainly supported.There is a strong peak near the Fermi level,and the light absorption will evidently increase over here.The distribution of charge density shows that the bands' densities are very big.There are covalence bonds and metal bonds in the studied system,and the metal bonds also come from the communized movements mainly.