Abstract: In this research, samples of pure polystyrene and Polystyrene (PS) doped with Wood Buckthorn Peel (WBP) were prepared using casting method. The effect of addition of Wood Buckthorn Peel (WBP) concentration on optical properties of poly styrene have been studied in the wavelength range 200-800 nm. The absorption coefficient, energy gap, refractive index and extinction coefficient have been determined. The results show that the optical constants change with increase of WBP concentration.