Abstract: The electronic structural properties of Cn (n=3~10) molecular wires are investigated systemically using the B3LYP density functional method under the basis set 6-311++g** level. By the analysis about the calculated results, it can be found that because of the effect of delocalization, the ground state of carbon molecular wires Cn is singlet as n is odd number, whereas the triplet is the stable ground state of carbon molecular wires Cn as n is even number. Meanwhile, based on the obtained equilibrium structures in ground state, the polarizability, charge distribution and energy level distribution of carbon molecular wires have been investigated. At the same time, the relationship between high occupied molecular orbits EH (HOMO), low virtual molecular orbits EL(LOMO) and the number n of carbon molecular wires is determined, i. e., EHn－2 < EHn < EHn+2, ELn－2 > ELn > ELn+2. Therefore, the fermi levels of carbon molecular wires display their own brand of odd-even alternation properties. The reason for these properties of carbon molecular wires is explained in present work.