Herein, the influence of platinum (Pt) catalyst on the interface between SiO 2 nanofiller and addition cure silicone rubber (ALSR) matrix is investigated with different concentrations of Pt catalyst. It is found through various tests that Si–O–Si covalent bonds and hydrogen bonds form at the interface with a moderate amount of Pt catalyst. Based on these observations, a model for the interfacial structure of ALSR/SiO 2 nanocomposites is proposed. In particular, it is demonstrated, without changing the mass fraction and surface modifier of the filler, a more compact interface is obtained by increasing the amount of added Pt catalyst by a few ppm, resulting in a 25% increase of breakdown strength, 10% increase in thermal conductivity, 50% increase in tensile strength, and a 31% increase in the elongation at break.