The silicone rubber（SIR） insulation of cable accessories has been in a durative temperature gradient environment caused by the heating of the cable core

and the complex electric field distribution has aggravated the deterioration of electrical tree. The suppression of electrical tree inception and growth is an effective means to avoid the failures of the cable accessory under the electrical and thermal coupling conditions. In this paper

the suppression effect of ethylene-vinyl acetate copolymer（EVA） on electrical tree was researched under the conditions of the temperature gradient of ± 60 ℃ and AC. The suppression effects of SIR/EVA blends on the inception voltages and growth of electrical tree were studied. According to the physical and chemical properties of SIR/EVA

the suppression mechanisms of electrical tree were discussed in SIR by employing EVA. The results show that the EVA can increase the electrical tree inception voltage

and the growth length of the electrical tree is significantly reduced

which has a better suppression effect on the electrical tree inception and growth in the SIR. The cross-linking of the SIR/EVA blends is uniform and the C=O double bonds with high bond energy enhances the tensile strength of SIR materials in a certain temperature range. The EVA improves the mechanical properties of SIR. The molecular chain break threshold is enhanced by the physical cross-linking between EVA and SIR. The thermal electrons transport is hindered by the crosslinked structure. Therefore

the electrical tree suppression ability is enhanced in SIR/EVA blends.