Generally nanoparticles in polymer matrix can improve the polymer properties. Nanoparticles can be used in Polystyrene composites as well as in electrospinning of Polystyrene. In previous researches, toxic and dangerous solvent such as Demethyl formaid and Tetra hydroforan was used in Polystyrene nano composites, but in this research we have used a natural and green Limonene solvent extracted from citrus fruits for the nanocomposite films and also for Polystyrene fibers. Finally we studied the properties of fibers and nanocomposite films. Here two types of nanoparticles; Zinc Oxide(ZnO) and Titanium Dioxid (TiO_2) were used to improve Polystyrene properties. In the first, the electrospun PS fibers from PS solution dissolved in d-limonene and DMF were compared. It was observed that the diameter of PS fiber from PS/d-limonene is larger than PS/DMF due to lower electrical conductivity of solvent. Then PS nanocomposits containing nanocomposites were prepared by PS solutions containing dispersed nanoparticles of TiO2 or ZnO. FE-SEM images revealed well dispersion of ZnO nanoparticles In the PS nanocomposites but results showed aggregation of results showed that PS fiber diameter decreased by increase in ZnO or TiO2 nanoparticles content. Results revealed the high UV-Shielding efficiency of nanocomposites for nanocomposite containing wt%. of ZnO or TiO2 nanoparticles, over 99% of UV light at wavelengths between 200 and 800 nm was observed. Optical traarency in the visible region of PS/Tio2 nanocomposites was slightly below that of PS/ZnO nanocomposite due to smaller size and aggregation of Tio2 nanocparticles. Nanoparticle had no effect on the WAXD pattern and FTIR spectrum of PS. The mechanical properties of nanocomposit such as a function of nanoparticle loading. Tensile increase with nanoparticles content. Also same result obtained for film of PS/ZnO , but tensile strength and module of TiO2/PS film showed an increase followed by a decrease at higher loading due to more aggregation of TiO2 nanoparticles. The Tg and TGA of pure PS and PS Nanocomposites were investigated. Thermal degradation temperature of PS nanocomposites increased with nanoparticles content. The glass-transition temperature of the PS/ TiO2 and PS/ZnO fibers increased with nanoparticle content, but this temperature decreased by increase in nanoparticles loaded of PS nanocomposite films.