This study aims to develop a novel computational model to accurately quantify the interfacial interactions between matrix resin and fillers in polymer-based composites, thereby overcoming the limitations of existing theories and computational models in assessing interfacial interactions, such as limited application scope and unclear boundary conditions. By exploring the dynamic behavior of matrix resin molecular chains, a theoretical model for interfacial interactions was constructed based on molecular chain dynamics theory, and corresponding computational formulas were derived. To validate the model, bisphenol A epoxy resin and hollow glass microspheres were selected as experimental materials, and experimental studies were conducted using dynamic thermomechanical analysis and other methods. The results demonstrate that the proposed molecular chain dynamics model can accurately quantify the interfacial interactions in polymer-based composites, successfully determining the interfacial interaction parameter A value of 0.42 between bisphenol A epoxy resin and hollow glass microspheres, which falls into the category of “ordinary interfacial interaction.” This study not only provides a solid theoretical foundation for the optimization design and performance enhancement of composites but also holds broad application prospects in fields such as military aviation, aerospace, naval equipment, and high-end terrestrial equipment, potentially driving advancements in composite material design technology.