Excited molecular structure in gas phase usually consists of two types of energy states: Rydberg states with diffused molecular orbitals and valencetype excited states with rather localized molecular orbitals. Excitation from molecular inner-shell orbitals into the above-men-rioned excited orbitals leads to near-threshold structures. Based on the multiple-scattering self-consistent field theory, we have studied the molecular near-threshold structure. Our theoretical results are in good agreement with experimental measurements. We have also elucidated:(1) The dynaimcal interaction between the excited electron with the residual molecular ion.(2) Physical orgin of the shaperesonance, namely, as an anti-bonding state embedded in the continuum.