Nanoparticles with good stability and suitable as Pickering emulsion emulsifier were prepared by the modification of soybean glycinin (SG) with the combined treatment of heating， ultrasonic and pH shifting. The optimal modification order， heating time (5-30 min)， ultrasonic amplitude (0-70%) and ultrasonic time (0-12 min) were determined by single factor and response surface methodology. The results showed that the optimal conditions for modification were heating at 95 ℃ for 20 min 19 s， ultrasonic at 43% amplitude for 5min 17s (750 W， 20 kHz) and pH treatment at 12 for 1 h with the best modified order of heating-ultrasonic-pH shifting. Under the optimal conditions of modification， the particle size and Zeta-potential of SG nanoparticles were the smallest and the storage stability (4 ℃) was the best. Meanwhile， the surface hydrophobicity was the highest， up to 3 516.16. As the ionic strength increased from 0 mol/L to 0.6 mol/L， the particle size increased significantly (P<0.05)， while the absolute value of Zeta-potential and solubility decreased significantly (P<0.05). The samples at 0 mol/L and 0.6 mol/L were stable at 4 °C for 12 d. With the heating temperature increased from 100 ℃ to 150 ℃， the particle size increased significantly (P<0.05) while the absolute value of Zeta-potential and solubility showed a trend of increasing first and then decreasing. The samples heated at 130-150 ℃ were stable at 4 ℃ for 5 d. The pH (2-10) had a complex effect on the particle stability. Although the particle size of the sample at pH 10 was the smallest and the potential and solubility were the highest， the storage time (4 ℃) of the sample at pH 2 was the longest， up to 20 d. The SG nanoparticles can withstand one freeze-thaw cycle at -80 ℃. This study provides a theoretical basis for the development of emulsifiers for Pickering emulsion and its application in food.