Conformational energies of the poly(tetramethylene oxide) chain in the thirdorder interaction approximation are calculated using semiempirical potential function method.Configurationdependent properties of poly(tetramethylene oxide) chain,such as the characteristic ratio, the dipole moment ratio and their temperature coefficients, are calculated using statistical weight matrix method based on the rotational isomeric state(RIS) model. Results show that these values are better than those obtained from the secondorder interaction approximation, and the characteristic ratio and the dipole moment ratio are in good agreement with experiment.