Clarifying the aggregation state of asphaltenes and the rheological properties of the system in aqueous environments is of great significance for petroleum exploration, development, and flow assurance. In this study, molecular dynamics simulations were employed to reveal the influence of different water contents (0.25~20 wt%) on the aggregation structure of asphaltenes and the molecular mechanism regulating the rheological behavior of water-in-oil (W/O) emulsion systems. The results indicate that as water content increases, asphaltenes transition from a bulk bridging aggregation state to an interfacial adsorption state, driven by electrostatic Coulomb interactions at the oil-water interface and further reinforced by hydrogen bond network formation. The system viscosity initially exhibits a slight increase followed by a gradual decrease. Water molecules weaken the associative interactions between asphaltenes and surrounding oil molecules by participating in aggregate formation, primarily governing the viscosity reduction, while the strength of aggregate structures formed between water and oil components exerts a secondary influence on the rheological behavior. This study provides new insights into the complex interactions at oil-water interfaces and their impact on W/O emulsion stability, offering theoretical guidance for regulating the rheology of oil-water systems.