Abstract: To develop a functional walnut meal protein-polysaccharide complex for improving the resource utilization of walnut meal protein and expanding its applications, this study focused on the modification of walnut meal protein via ultrasound-assisted wet glycosylation. And the walnut meal and black fungus polysaccharid were used as raw material, and the effects of key process parameters—including ultrasound power, pH, ultrasound duration, and the mass ratio of walnut meal protein to black fungus polysaccharide—on the grafting degree and browning level of walnut meal protein were first investigated. Subsequently, response surface methodology (RSM) was employed to optimize the preparation process and determine the optimal conditions. Additionally, the functional properties of the modified walnut meal protein were systematically determined. The results demonstrated that under the optimal conditions—mass ratio of walnut meal protein to black fungus polysaccharide of 1:2, reaction temperature of 80 ℃, pH of 9.60, ultrasound power of 295 W, and ultrasound time of 9.6 min—the grafting degree reached 48.60%, which was in close agreement with the predicted value. Polyacrylamide gel electrophoresis (PAGE) analysis confirmed the successful preparation of walnut meal protein glycosylation products via ultrasound-assisted wet Maillard reaction. Scanning electron microscopy (SEM) observations revealed that the modified walnut meal protein exhibited a reduced particle size and a spherical micro-particle morphology. Functional property assays showed that the solubility, water-holding capacity, and emulsifying activity of the ultrasound-assisted wet glycosylation-modified walnut meal protein were 1.61-fold, 2.25-fold, and 1.62-fold those of the unmodified protein, respectively. Compared with the wet glycosylation-modified counterpart, the ultrasound-assisted modified protein displayed 1.12-fold higher solubility, 1.65-fold higher water-holding capacity, and slightly improved emulsifying stability (P<0.05). This study provides a theoretical and technical reference for improving the resource utilization of walnut meal protein and broadening its industrial applications.