<p>Silicone rubber will be affected by both thermal and mechanical aging during the operation of cable accessories, resulting in stress relaxation. This leads to stress mismatch within cable accessories, thereby reducing the insulation performance of the interface. In order to enhance the stress relaxation resistance of silicone rubber, kaolin with excellent electrical insulation performance is used as the filler to prepare kaolin/silicone rubber composite materials, and through experiments, the improvement in material properties and the underlying mechanism were verified. The experimental results show that after adding kaolin, the stress relaxation resistance of the silicone rubber is enhanced. Among them, the composite material with a 10&#xa0;wt% kaolin loading achieved the best compressive stress relaxation resistance, and compared with pure silicone rubber, the tensile strength increased by 10.35%. Furthermore, after adding kaolin, the electrical insulation performance of the material is improved synergistically. Molecular simulation calculations show that with the increase of kaolin content, the free volume of silicone rubber decreases and the mean-square displacement decreases, which macroscopically modulates the compressive stress relaxation characteristics of silicone rubber materials. This work provides valuable insights for improving the comprehensive performance of silicone rubber for cable accessories.</p>