Controlling the friction coefficient is crucial for smart friction management and the reduction of energy consumption. The exploration of the mechanisms for regulating friction coefficients is at the core of this issue. In this study, it is proposed that microviscosity plays a pivotal role in influencing the rapid response of the friction coefficient variation in polymer-water-based lubrication systems. The change in microviscosity induced by salt ions was investigated using fluorescent probes and molecular dynamic simulation. The friction contact region was divided into core, corona and blank regions based on functional specificity to investigate microviscosity. The results of the study showed that the microviscosity exhibited by salt ions which are more readily adsorbed in the corona region is the key to determining changes in the friction coefficient. The high microviscosity in the core region of the polymer coating serves as the basis for maintaining a low friction coefficient. The blank region ensures low shear viscosity during friction. Therefore, the regulation of the friction coefficient can be achieved by controlling the microviscosity in the corona region using salt ions. This study not only presents a novel method for characterizing microviscosity but also establishes a theoretical basis for the intelligent regulation of friction.