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The optical and bonding characters of doping ZnSe quantum dots are investigated in this paper in theory and experiment.Cd,Mn and Cu doping ZnSe have been synthesized with good blue or orange luminescence.In experiment,we have found that Mn and Cu doping ZnSe quantum dots have the same wavelength of absorption spectra with pure ZnSe quantum dots.Cd doping ZnSe quantum dots have different one with ZnSe.Moreover,absorption spectra of Cd-ZnSe quantum dots shift to red with higher speed than those of Cu-ZnSe and Mn-ZnSe.We have thought that it is the different orbitals resulting in this phenomenon.Then,we calculated Molecular Orbital(MO)of these clusters.The calculated results show that doping Cd,Mn and Cu ZnSe quantum dots have different MO.Highest Occupied Molecular Orbital(HOMO)and Lowest Unoccupied Molecular Orbital(LUMO)of Mn belong to range of ZnSe,which caused Mn-ZnSe quantum dots have same wavelength of absorption spectra and different luminescence.LUMO of Cu is in the scope of ZnSe.And HOMO of Cd is in the range of ZnSe.Thus,Cu-ZnSe quantum dots have same wavelength of absorption spectra.Luminescence of ZnSe quantum dots are influenced by Cu.Cd-ZnSe quantum dots have different absorption spectra because Cd has changed the transition of orbital.In this way,Luminescence of Cd-ZnSe are different with ZnSe quantum dots.