The polysaccharide extracted from Vicia ervilia seeds were treated with gamma-irradiation at doses of 5-15 KGy. Then the structural, physicochemical, and functional properties of irradiated and non-irradiated polysaccharides were studied. According to the results, with increasing radiation dose, the average molecular weight of polysaccharides decreased, and the particle size increased. The results of HPLC showed that the values of glucose, rhamnose, and uronic acid increased because of gamma-irradiation. A comparison of the structure of irradiated and non-irradiated polysaccharides by FTIR and NMR spectra showed that irradiation led to the increase of hydroxyl groups. According to the findings of this research, irradiation resulted in improved the capacity of oil and water absorption, the capacity of emulsion, and the emulsion stability of polysaccharides. In addition, the results exhibited that gamma-irradiation improves the antioxidant activity and prebiotic potential of polysaccharides by modifying physicochemical characterization without changing the functional groups.