In order to improve the freezethaw stability of soy protein, wet glycosylation modified soy protein isolate was tested in the irradiation field, and the modification process was optimized by using the degree of grafting and cream index as indicators. The results showed that the freezethaw stability of SPI prepared under the conditions of the mass ratio of soy protein isolate (SPI) and maltose (M) 4, SPI mass concentration 40mg/mL, and irradiation dose 7.5kGy was significantly improved. Compared with unmodified SPI, the emulsion cream index of the modified SPI after three freezingthawing cycles was decreased by 22.98 percentage points, 28.40 percentage points and 30.70 percentage points, respectively, and the oiling off was decreased by 9.7 percentage points, 21.2 percentage points and 26.4 percentage points, respectively. Emulsifying activity index and emulsifying stability index were increased by 9.26m2/g and 3.76min, respectively, compared with that of unmodified SPI. Infrared spectroscopy analysis indicated that the maltose molecule was bound to soy protein isolate in the form of covalent bonds. Scanning electron microscopy showed that the microstructure of SPI-M irradiated was honeycomb and showed good water holding capacity. The results of optical microscopy showed that compared with the unmodified SPI emulsion, only small oil droplets appeared in the SPI-M emulsion after freezethaw treatment, and the emulsion state was more stable. The research result provided theoretical and technical reference for the production of soy protein with high freezethaw stability. 