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The influence of the organic ionic salt crystal 4-N,Ndimethylamino-4-N-methyl-stilbazolium tosylate (DAST) and 4-(N,N-dimethylamino)-4 0 -nitrostilbene (DANS) dyes on structure, and piezoelectricity of Poly (styrene-co-acrylonitrile) (SAN) copolymer has been studied by several techniques. X-ray diffraction and optical microscopy reveal crystalline phase in the doped copolymer and the degree of crystallinity increases either by increasing dye's concentration or by applying stress to the films. Fourier Transform Infrared spectroscopy (FTIR) spectra showed that the intensity of the vibrational band of SAN copolymer increased with the dye concentration, indicating the interaction between dyes and the copolymer. The dynamic glass transition temperature (T g ), probed by Thermally Stimulated Depolarization Current (TSDC), related to the segmental mode of SAN (at $373 K) is slightly shifted to lower temperature by adding DANS, while it shifts to higher temperature upon adding DAST ($390 K). Suppression and enhancing in the current intensity of SAN is related to the dipolar strength of dyes.