The interaction between polysaccharides and proteins in co-adsorption played a critical role in determining interfacial properties and emulsion stability. This study focused on the regulation mechanism of different concentrations of polysaccharide on the dynamic adsorption behavior of protein particles at the subunit level, and how the interfacial membrane microstructure affected the stability of emulsion. The research demonstrated that Konjac Glucomannan (KGM) and β-conglycinin (7S) formed stable composite through non-covalent interactions such as hydrogen bonding and hydrophobic interactions. Additionally, low concentrations of KGM promoted the unfolding of 7S structures, enhancing the wettability of the 7S-KGM composite by modulating the hydrophilic-hydrophobic balance. The results from interfacial adsorption kinetics and Quartz Crystal Microbalance with Dissipation Monitoring (QCM-D) indicated that KGM could synergistically facilitate the initial diffusion, penetration, and rearrangement of 7S at the oil-water interface thus forming a dense and viscoelastic three-dimensional gel-like multilayer interfacial structure. Notably, high-density adsorption of the 7S-KGM composite at the interface significantly increased the thickness and the protein content of the interfacial layer, enhancing emulsion stability. Finally, The results of dissipative particle dynamics simulations further demonstrated that the synergistic adsorption of KGM enhanced the interfacial adsorption efficiency of 7S, thereby stabilizing the interface more effectively and reducing droplet size. These findings of experiments and simulations provided insights into the mechanisms by which polysaccharides enhanced protein emulsification performance at the subunit level, offering critical guidance for optimizing protein interfacial properties and enhancing emulsion stability.