Abstract: To improve the functional properties of Walnut protein isolate (WalPI), WalPI was modified using cold plasma (CP). The effects of different voltages of CP (0, 50, 60, 70, 80, and 90 V) on the structural and functional properties of WalPI were investigated. The results showed that the secondary structure of WalPI was disordered the tertiary structure unfolded after CP treatment, and the functional properties were improved. 80 V showed the best overall performance of WalPI, with the maximum fluorescence intensity and ultraviolet absorption peak intensity, the free sulfhydryl content of 57.89 μmol/g, and the thermal denaturation temperature reduced to 85.95 ℃, with the transformation of α-helical structure, irregular coiling into β-folding and β-rotation, the protein structure was highly crystallized. The solubility, water-holding ability (WHC), and oil absorbing capacity (OAC) reached the maximum values, with an average particle size of 763.96 nm, and a uniformly dispersed globular microstructure. The CP treatment altered WalPI's structure, improved its functional properties, and expanded WalPI's resource utilization.