To improve the solubility of soy protein concentrate (SPC)obtained by acid precipitation, a process of physical modification was developed. The major operating parameters affecting NSI, including water medium temperature, pH of the protein solution and duration of ultrasonic treatment were investigated. After treatment with 300 W and 25 kHz ultrasonic in water medium at 100 ℃ and pH 9 for 30 min, the NSI of the SPC improved from 64. 00% to 88.06%. Furthermore,the modified SPC showed higher capabilities of emulsification, oil adsorption...