The effects of different sterilization conditions on the physicochemical properties of soybean protein isolate (SPI) during frozen storage were studied to gain scientific knowledge and provide basis for supplying soy foods with good quality. SPI was prepared after sterilized at 65℃, 90℃ and UHT (denoted as 65SPI, 90SPI and USPI), respectively. The changes of physicochemical properties of protein dispersions (2%, pH value 7.0) subjected to frozen storage at -18℃ were investigated. The results showed that three types of sterilization all resulted in heat denaturation of proteins. Compared with control SPI, the soluble proteins content and free SH groups of 90SPI and 65SPI were dropped sharply while the viscosity and particle size were increased greatly. However, there were no marked changes of USPI. In addition, hydrophobic domains of 90SPI and USPI were exposed to a higher extent and their AB subunits were in dissociation state according to non-reducing SDS-PAGE. SPI with different sterilization treatments underwent different chemical and physical changes during frozen storage. The solubility, viscosity, free and total SH groups of protein trended down gradually with the increase of frozen time, while particle size and exposed extent of hydrophobic domains were increased during frozen storage. Some soluble aggregations associated with disulfide bonds were observed in the SDS-PAGE electrophoresis of 65SPI and 90SPI solutions after frozen storage.