Abstract: Polymer blends were prepared by thermo-pressing mixtures of soy protein isolate(SPI) and poly(vinyl alcohol)(PVA) using glycerol as a plasticizer. The properties of the blends were investigated using differential scanning calorimetry analyzer, thermogravimetry analyzer, universal electronic tensile testing machine, and scanning electron microscopy. The SPI/PVA blends possessed better compatibility when the content of PVA was lower. As the increase of PVA contents, there was the second Tg of SPI/PVA blends at the around of 130℃, and its glass transition temperature was higher. The addition of PVA significantly boosted the thermal stability, and the 24 h water absorption of SPI/PVA decreased from 85.5 % to 54 %, When the content of PVA was 30%, the tensile strength of SPI/PVA increased by 237 %, compared with pure SPI.