Abstract: In this study, layer-by-layer assembly was performed to prepare sodium alginate (SA)?layer and walnut-peptide–chitosan (CS) bilayer composite films. Genipin was adopted to crosslink?CS and walnut peptide. The properties of walnut peptide-CS-SA composite film were determined,?and the influence of material ratio on the performance of composite film was explored. According?to the results, the mechanical tensile property, oil absorption property, and water vapor barrier?property of the composite film were improved with the presence of genipin. Moreover, the proportion?of CS and walnut peptide had significant effects on color, transmittance, mechanical properties,?barrier properties, and antioxidant properties of the composite films. Among them, the composite?film containing 1% (w/v) CS, 1% (w/v) walnut peptide, and 0.01% (w/v) genipin showed the best

performance, with a tensile strength of 3.65 MPa, elongation at break of 30.82%, water vapor permeability?of 0.60 g.mm.m-2.h-1.kPa-1, oil absorption of 0.85%, and the three-phase electrochemistry?of 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging rate of 25.59%. Under this condition, the?tensile property, barrier property, and oxidation resistance of the composite film are good, which can?provide a good preservation effect for food, and has great application potential.