Abstract: Using the first vacuum side stream of SZ36-1 as raw material, the feasibility of producing transformer oil base oil was verified in a pilot plant industrial trial production at the diesel hydrogenation unit of CNOOC Taizhou Petrochemical Co., Ltd. without changing the process flow. When the fresh feed rate was 25 t/h, the product circulation rate was 15 t/h, the volume space velocity was 0.96 h^-1, the reaction pressure was 7.0 MPa, the inlet temperature of the reactor was 345 °C, and the volume ratio of hydrogen to oil was 600, the product transformer oil basic oil could meet the general physical and chemical properties requirements of transformer oil quality index (GB 2536- 2011) . The calculation results of the process parameters of the industrial unit show that the diesel hydrogenation unit can be used to produce transformer oil base oil with little modification of equipment.

Key words: diesel hydrotreating, naphthenic base crude, transformer oil, bas oil