In this paper, we report the studies on gel polymer electrolytes (GPEs) films consisting polyvinylidenefluoride-cohexafluoropropylene (PVdF-HFP), sodium trifluoromethanesulfonate (NaCF3SO3), ethylene carbonate (EC) and propylene carbonate (PC). The ionic conductivity of the GPE films was found to depend on the salt concentration that added to the films. The ionic and cationic transference numbers of GPE films were estimated by DC polarization and the combination of AC and DC polarization method, respectively. The results had shown that both ionic and cationic transference numbers are consistent with the conductivity studies. The electrochemical stability of the GPE films was tested using linear sweep voltammetry (LSV) and the value of working voltage range appears to be high enough to be used as an electrolyte in sodium ion batteries. The cyclic voltammograms for the GPEs film exhibit good cycling performance and the studies confirmed the sodium ion conduction in the films.