We investigate the mechanism of strong fluorescence and phosphorescence observed in the binuclear copper complexes by means of a discrete variational (DV)-Xα molecular orbital calculation. Comparing to the energy differences among a occupied and unoccupied molecular orbitals, we can reveal the photon energy of the light of the luminescence in a quantitative way. We also obtained the strong relationship between the observed and the calculated photon energies with according to the conservation of energy principle.