Abstract: In the present paper, an appreciable enhancement and its mechanism of some ligands on the atomic absorbance of Cu by aspirating directly the solution into a flame atomic spectrophotometer have been studied.In the presence of the chelating agents,Cu shows an obvious enhancing effect on the atomic absorption, but Zn, Cd, Fe without showing any effect. The difference of the enhancing effect is explained with the bond dissociation energy and the electronic configuration for the ground level of atom.An addition of few micromoles of the corresponding chelating agent to the series of the standard solution, the enhancing effect on the atomic absorbance of Cu for the flame atomic absorption spectroscopic analysis is repaired.