Nanosized ZnO (n-ZnO) were prepared by a wet-chemical method. The polymer-based composite electrolyte films were obtained using solvent casting method by the addition of nanosized ZnO particles to polyethlene oxide (PEO) and anhydrous lithium perchlorate (LiClO4). SEM were used to characterize the dispersion of n-ZnO in (PEO)(16)LiClO4/n-ZnO composite films. DSC were used to characterize the T-m, T-g and crystallinity of composite films. The ion conductivity of composite polymer electrolyte was measured by AC impedance method. The results indicate that by addition of 10wt% n-ZnO particles, the ionic conductivity at room temperature of the (PEO)(16)LiClO4 is enhanced by forty times, which is attributed to the content and dispersion of n-ZnO particles. In addition, the interface between n-ZnO and polymer play a certain role in enhancing conductivity of the polymer electrolyte.