High temperature heat transfer medium silicone oil of solar photothermal power generation system: in order to improve the efficiency of power generation, the working temperature of the heat transfer medium of solar photothermal power generation system is as high as 400 ℃. The general-purpose heat transfer oil can not only meet the requirements of safe working temperature, but also the heat-resistant performance of the heat transfer oil will be reduced due to the mechanical shear molecular chain breaking during the long-term pumping operation. Silicone oil with semi-inorganic and semi-organic polymer structure has excellent heat resistance and shear resistance of polymer molecules, which can be used as a heat transfer medium for photothermal power generation. The specific structure of benzyl silicone oil not only has excellent heat resistance and shear resistance, but also has outstanding heat resistance and oxidation resistance. At the same time, additives such as heat stabilizer are introduced to further improve the thermal stability of silicone oil. The application of benzyl silicone oil as the efficient heat transfer medium can ensure the long-term stable operation of the photothermal power generation system.