In the present study, solid film of poly (3,4-ethylenedioxythiophene):polystyrenesulfonate, (PEDOT:PSS) has been prepared by casting its aqueous solution at room temperature and are characterized by using X-ray diffraction and differential scanning calorimeter. The temperature-dependent behavior of the ac and dc conductivity of the PEDOT:PSS film has been investigated. The temperature dependence and scan rate dependence of J-V characteristic curves have been tested. The study of frequency dependence of ac conductivity in a wide range of temperature up to 443 K, indicates that the dominant conduction mechanism in PEDOT:PSS film is Overlapping-Large Polaron Tunneling (OLPT). The study of the electrical conduction with applied voltage shows a reversible negative differential resistance (NDR) through the turnover point (T.O.P) for Cu/PEDOT:PSS/Cu device. Threshold current density, J_th, and threshold voltage, V_th at T.O.P as well as NDR are strongly affected by ambient temperature up to 383K and scan rate up to 3V/sec.  The turnover behavior has been explained according to a competition between high conduction due to schottky emission and NDR due to field-induced of electrical polarization in conduction paths.