Abstract: During the operation of cable accessories for locomotives, they are not only in an environment where the temperature is constantly changing, but also affected by the swelling of the interface coated with silicone grease for long-term operation. These factors will pose a certain threat to their safe and reliable operation, however, the related research has not been found in the literature. In this paper, according to the extreme ambient temperature (−40~90 ℃) of the actual locomotive operation, the silicone grease with excellent performance was selected. The effects of high- and low-temperature cycle aging combined with the swelling effect of silicone grease on the molecular structure, electrical properties and space charge distribution of cross-linked polyethylene and silicone rubber were studied. The results show that the internal structure of crosslinked polyethylene is destroyed after high- and low-temperature cycle aging and coating silicone grease, and the conductivity and dielectric constant of the sample increase to a certain extent after aging. Under the condition of only high and low-temperature cycle aging, aging promotes the re-crosslinking of molecular chains, which reduces the conductivity of the sample, while aging also increases the density of polar groups, resulting in an increase in the dielectric constant of the sample. After the silicone rubber coated with silicone grease is aged at high- and low-temperatures, the molecular structure is destroyed due to the swelling effect of silicone grease, which enables the conductivity and dielectric constant of the material to increase significantly. The polarity and conductivity of cross-linked polyethylene and silicone rubber determine the properties of the interfacial charge of the interlayer of crosslinked polyethylene/silicon rubber(XLPE/SiR). The silicone rubber coated with silicone grease has high conductivity, strong polarity and significant interfacial charge accumulation after aging, and the internal charge accumulation of silicone rubber is obvious due to the swelling effect of silicone grease.