Abstract: Background To investigate the effects of vermicompost on soil surface electrochemical properties and aggregate stability, and to clarify the electrochemical mechanisms by which vermicompost regulates soil aggregation. Methods This study focused on Dark loessial soils from the Gully Region of the Loess Plateau. A laboratory incubation experiment was conducted with five vermicompost application rates (0%, 2.5%, 5%, 7.5%, and 10%). The soil surface electrochemical properties and aggregate stability indices were measured, and structural equation modeling (SEM) was employed to decipher the driving pathways. Results 1) The application of vermicompost significantly altered the soil surface electrochemical properties. Compared with the control (CK), the Zeta potential, surface charge density, and electric field intensity decreased by 73.71 - 151.14%, 4.26 - 29.79%, and 3.95 - 29.14%, respectively. Conversely, the specific surface area and surface charge quantity increased by 12.76 - 66.22% and 7.42 - 17.59%, respectively. 2) Vermicompost application optimized the soil aggregate size distribution, promoting the conversion of microaggregates into macroaggregates and enhancing their stability. The mean weight diameter (MWD) and water-stable aggregate rate (WSAR) increased by 8.15 - 110.07% and 64.70 - 149.69%, respectively. 3) Soil surface electrochemical properties play a critical mediating role between vermicompost and soil aggregate stability, with Zeta potential and specific surface area (SSA) being the dominant factors influencing aggregate stability. Conclusion By leveraging electrochemical characteristic parameters, this research offers a new perspective and robust theoretical foundation for optimizing soil structure and managing soil erosion in the Loess Plateau.