Abstract: Epoxy tung-maleic anhydride adhesive is an important part of high voltage electrical machine main insulation, and affects the stable and safe operation of electrical machine directly. In order to improve the mechanical and aging property of the epoxy tung-maleic anhydride adhesive, the nano-SiO₂/epoxy tung-maleic anhydride adhesive composites with the mass fraction of 1 wt%, 2 wt%, 3 wt% and 4 wt% nano-SiO₂ were made respectively. The flexural strength and impact strength, and the breakdown strength before and after thermal aging and electrical aging of the composite were measured. The results indicate that flexural strength of 1 wt% nano-SiO₂/epoxy tung-maleic anhydride adhesive composite increases by 24. 79%, and impact strength of 2 wt% nano-SiO₂ loading composite increases by 47.11%. Before the aging, the breakdown strength of the composites increases with the increasing of nano-SiO₂ loading first, and then decrease. When the nano-SiO₂ loading is 2 wt%, the breakdown strength of nano-SiO₂/epoxy tung-maleic anhydride adhesive reaches the maximum and increases by 7.3%. After electrical aging as well as at early period of the thermal aging, the breakdown strength of 1 wt% and 2 wt% nano-SiO₂ loading composite are higher than that of the unfilled adhesive. But at the end of 28 days thermal aging, the breakdown strength of all the composites and unfilled epoxy tung-maleic anhydride adhesive tend to be same.