Abstract: The application and development of pea protein in the food industry are limited by issues such as poor solubility and insufficient emulsifying properties. In this study, succinic anhydride (SA) was used to modify pea protein isolate (PPI), and the effects of different SA addition levels on the molecular conformation and functional properties of the protein were investigated. The results showed that the SA addition level was positively correlated with the acetylation degree of PPI; when the mass ratio of SA to PPI was 0.1:1, the structural and functional properties of PPI improved most significantly. The absolute value of the zeta potential of the modified PPI increased significantly, and surface hydrophobicity decreased. Fourier transform infrared spectroscopy revealed a reduction in the α-helix content in the protein’s secondary structure, along with an increase in random coils and β-sheets, indicating protein denaturation and enhanced conformational flexibility. At the same time, the solubility, emulsifying activity, and emulsifying stability of PPI were all significantly improved, particle size decreased, and dispersibility improved. Scanning electron microscopy revealed that the modified protein exhibited a more extended and loose free structure. In summary, succinylation modification effectively improved the solubility and emulsifying properties of PPI by altering its charge distribution and conformational characteristics, significantly enhancing the properties of PPI and providing a theoretical basis for the large-scale industrial application of pea protein.