Abstract: The molecular structures of polythieno3,4-c furan,polypyrrole series were optimized with DFT B3LYP method.The polymers are calculated by periodic boundary conditions(PBC) and LSDA method.All calculations were performed with 6-31G* basis sets.The relationship between electronic structure of monomer,oligomer and polymer was investigated.Meantime,the band structures and state density of polymer were analyzed.Study shows that the conductivity of bicyclic molecule is better than that of monocyclic molecule.The theoretical Eg is only 0.19 eV,so they can be potential conductors.