Vegetation restoration can input amounts of organic matter into soils to improve soil aggregate stability; for this process, the interaction between organic matter and charged soil particles is a key. However, the molecular-scale knowledge about organic matter-mineral interactions remains largely qualitative. Here, we analyzed soil particles surface electrochemical properties and soil internal forces (electrostatic, hydration , and van der Waals forces) along vegetation restoration to quantitatively evaluate how SOM increase the stability of soil aggregate. Our results revealed that the enrichment of SOM after revegetation increased the cation exchange capacity (CEC), specific surface area (SSA), and soil surface charge density (σ0), thereby strengthening the electrostatic repulsive pressure. Besides, the increasing SOM led to the increase in Hamaker constant at the molecular level and thus enhanced the van der Waals attractive force. As a result, the net pressure of soil internal forces was repulsive and decreased with increasing SOM during vegetation restoration. Meanwhile, the net pressure increased first and then leveled off with the decrease of electrolyte concentration in the bulk solution. The determined soil aggregate breaking strength showed similar trends to that of net pressure. Soil aggregate stability under different succession stages followed the order of farmland < grassland < shrub < forest. Overall, the experimental results of soil aggregate stability were in excellent consistent with the theoretical predictions of soil internal forces. Consequently, we conclude that organic matter input during vegetation restoration increased aggregate stability mainly due to the decrease of the repulsive net pressure of soil internal forces.