In this paper, we report the synthesis and properties of a series of composite polymer electrolytes formed by dispersion of a non-ionic organic plastic material succinonitrile (SN) into poly(vinylidene fluoride-co-hexafluoropropylene) (P(VDF-HFP)) complexed with four kinds of lithium salts. The addition of SN greatly enhances ionic conductivities of the electrolytes which is due to the high polarity and diffusivity of SN. The integrity of the plastic-crystalline phase is kept at low temperature range in polymer electrolytes. The high solubility of SN on Li salts is observed by Fourier transform infrared (FTIR) spectra measurement, thus could lead to enhanced lithium-ion transference number. The battery performances of composite polymer electrolytes at different temperatures are tested and the results are comparable to that of the pure plastic crystal electrolytes.