A new type of dual-phase polymer electrolyte (DPE) film was prepared by mechanical mixing of a poly(epichlorohydrin-co-oxirane) (ECO) and poly(acrylonitrile-co-butadiene) rubber (NBR) binary solution and then by solution casting. Both of the polymers are commercially available. The casting films were swollen with a LiClO4/propylene carbonate (PC) solution to obtain DPE films. The ionic conductivity of the DPE films was calculated on the basis of alternating current impedance measurements. The results showed that the ionic conductivity is dependent on the content of the LiClO4/PC solution and the ECO/NBR blend ratio. High ionic conductivity (>10(-3) S/cm at 298 K) was achieved when the ECO content in the matrix is 90% (w/w), the contentration of LiClO4/PC solution is at 3 mol/L, and the weight percent of LiClO4/PC is 40. The impedance spectrum provided evidence that a dual-phase structure was created, in which the ECO phase provided an ion-conductive pathway and the NBR phase acted as a supportive matrix. A new ionic conductivity mechanism was proposed.