Abstract: The electronic structures of a set of the Fe dioxygen complexes have been studied by using CNDO/2 computational method.The results showed that the apposite electronegativity of Nclement which is in aπ conjugated position ol the equatorial ligand and close by the central metal ion Fe(Ⅱ) between Cand Oelements has stabilized a low valence state and lias adjusted d orbital energies of the central metal Fe(Ⅱ),so that the electronic migration.Fe(Ⅱ) (d_xz,d_yz)→O₂(π_A) is forwarded and the electronic migration O₂(π_B)→Fe(Ⅱ) (d_z²) is prevcnted The experimental results arc satisfyingly explained on the basis of this computation.