DFT calculations of new polymer salt complex NaAsF6·PEO8 have been carried out in its low-temperature (LT) phase for the purpose of understanding the relationship between the structure and ionic transport in this material. Both relaxation at 0K and finite-temperature ab initio molecular dynamics approach up to 273K reproduced the LT structure very well. Nudged elastic band method has been used for estimating the migration barriers for collective migration of cations or anions in PEO tunnel-direction. The migration barriers were 1.25eV per anion and 1.6eV per cation which could explain the lower t + value as reported from experiments. AsF6 − anion exhibits rotational disorder about the three crystallographic directions of which the y-direction is least hindered.