Abstract: Abstract: There is an increasing interest in edible materials made of natural biopolymers in attempting to replace non-biodegradable plastics or films. Protein-based edible film has attracted more attention due to its low cost and superior barrier and mechanical properties, which attributed to strong intermolecular cross-linking of protein. However, protein-based films, due to the strong interactions and hydrophilicity of protein molecules, have relatively low tensile strength(TS) and elongation and poor water resistance compared to synthetic films, consequently limiting the commercial employment of peanut protein film in food applications. Therefore, modifications of proteins are necessary to improve the properties of peanut protein films. In this paper, peanut protein isolate (PPI) extracted from peanut meal was modified by sugar grafting with xylose, mannose, lactose, galactose, glucose and sucrose respectively. Peanut protein films made of the modified protein were prepared by casting. And the effects of sugar grafting on the physical properties such as mechanical properties including tensile strength and elongation at break (EB), opacity and solubility of peanut protein films have been studied.The results showed that sugar grafting improved the physical properties of peanut protein films significantly. Tensile strength of films could be enhanced by sugar grafting, and films with xylose exhibited the highest tensile strength, which was 1.77 times of the PPI control film. TS of films increased with the increasing of sugar concentration at low sugar level, but decreased when the ratio of PPI to sugar was lower than 10. The films grafted by glucose showed the highest EB of 255.22%, followed by xylose and EB of X-10（peanut protein film with a weight- ratio of peanut protein isolate to sugar as 10，the same as below）and X-20 were 1.66 and 1.67 times of the PPI control films. Meanwhile, opacity of peanut protein films were not affected by sugar grafting except xylose and galactose grafting which decreased the opacity of films with the increasing of sugar concentration. On the other hand, all the protein films except the ones modified by xylose dissolved after soaked into water with the solubility of 93.80%-97.89%. Solubility of films was reduced after xylose grafting, with the lowest solubility of 60.80%. As the xylose content increased the solubility of films decreased significantly, and X-5, X-10 and X-20 remained intact in water for 24 h.In conclusion, the effect of xylose grating was better than other sugars. Modification of PPI with xylose grafting can markedly improve the properties of peanut protein films, especially mechanical properties and solubility. When the ratio of peanut protein to xylose was 10, tensile strength and elongation at break of peanut protein film were 1.48 MPa and 218.92%, respectively. Solubility of protein film dramatically decreased from 96.94% to 60.80% after modification, and the films kept intact and integrated after immersion in water for 24 h. Results suggested that peanut protein isolate modified with xylose was potential for improving mechanical properties and increasing resistance of protein films to breakdown in water. Thus, the improvement raises the possibility of employing such new films as edible films for food packaging application. The research provided the theoretical foundation for the performance improvement and further development of peanut protein film.