Phenyl silicone fluid is the product of methyl silicone oil partially substituted by phenyl, with small thermal expansion coefficient，Colorless or yellowish transparent oil. Flash point > 300 ℃. The freezing point of silicone oil containing 5mo1% phenyl is as low as - 70 ℃, and the surface tension is about 2.1 × 10-4～2.85 × 10-4n / cm, relative density 1.00-1.11, refractive index 1.425-1.533. Good thermal stability. The gel time in hot air at 250 ℃ is 1750h. It also has good radiation resistance and high oxidation stability, heat resistance, flame resistance, UV resistance and chemical resistance. It can be prepared from the hydrolysates of octamethylcyclotetrasiloxane, dimethyltetraphenyldisiloxane and methylphenyldiethoxysilane through the polymerization reaction in the presence of a catalyst. It is used as a carrier for lubricating oil, heat exchange liquid, insulating oil and gas-liquid chromatography. It is used for insulation, lubrication, damping, shockproof, dust-proof and high-temperature heat carrier. It is an ideal liquid damping dielectric fluid for electronic instruments.