The structural configurations and electronic properties of polythiophenecyclodextrin (PT-CD) inclusion complexes have been investigated by a combined quantum mechanics and molecular mechanics method. The results show that the structure of n-type PT in CDs has a quinoidlike form. In the cases of beta-cyclodextrins and cross-linking alpha-cyclodextrins the electronic structure of polythlophene is almost the same as that of polythiophene in free space. The dopants are located outside the CDs, and hence for realization of a doped polymer chain it is important to control the separation distance between CDs, which can be easily achieved in the case of a molecular nanotube of crosslinking alpha-CDs.