By means of the wet chemical surface modification, the surface of CeO2 was modified by vinyltrimethoxysilane (VTMS). Infrared spectroscopy was used to investigate the structure of the modified CeO2 and the result showed that VTMS has been attached onto the surface of CeO2. Effect of VTMS concentration on the active index of the modified CeO2 was also studied, and the result indicated that the active index of the modified CeO2 increases with the increase of VTMS concentration and the optimal concentration of VTMS is 10 wt%. The effect of the modified CeO2 on the tear strength of silicone rubber before and after aging was studied and it was found that in comparison with the unmodified CeO2 the addition of the modified CeO2 results in the significant increase of the tear strength before ageing due to the increase of the crosslinking density of silicone rubber under the experimental conditions. The tear strength of silicone rubber filled with the modified CeO2 after ageing is higher than that with the unmodified CeO2, indicating that the modification of CeO2 can improve the heat-resistance of silicone rubber.