Dielectric investigations of films of different composition copolymers based on acrylonitrile (AN) with and without filler-salt LiClO4 in wide temperature-frequency ranges have been carried out. A single dipole-segmental relaxation process was observed. The region of occurrence of this alpha-relaxation process is shifted to higher or smaller temperatures depending on the chemical structure of the copolymers. The addition of salt LiClO4 to the copolymer films results in the decrease of the dielectrical loss factor, sharp limitation of polymer chains mobilities, shift of dipole-segmental relaxation region in the direction of higher temperatures, increase of relaxation times of the dipole-segmental process and also the appearance of two a-relaxation regions for some copolymer systems. It was caused by the formation of coordination bond between the Li+ cation and the electron pair on nitrogen atoms in the molecules of AN. The values of effective conductivities for the composites were lower then for copolymers at the temperatures T>Tg. It was caused by the increase of ion-polymer interaction.