Abstract: Advancements in computer technology promote the widespread application of molecular simulations in studying transformer insulation materials and nano-modification. Current research focuses on nanoparticle effects on insulation materials under static conditions, but rarely studies their modification mechanisms during electrical aging. Consequently, we established molecular models with different contents of SiO₂/cellulose, and adopted aging treatment process to investigate the changes in the microstructural parameters of the cellulose modified by SiO₂ under the influence of electro-thermal coupling. The study indicates that the thermodynamic and dielectric properties of the cellulose model are primarily influenced by the temperature. Introducing an electric field will amplify the temperature's impact on the cellulose and speed up the aging process. Adding SiO₂ particles can enhance the thermodynamic and dielectric properties of the cellulose, and there is a threshold for the modification effect. The 5% SiO₂/cellulose model has the best modification effect. The findings suggest that restricting molecular chain movement to enhance the compatibility between SiO₂ and cellulose are crucial for enhancing the anti-aging performance of the insulation materials. The results can provide a theoretical support for a deeper understanding of the nano-modification mechanism and guiding improvements in insulation materials.