Abstract: The technology of processing mixed feed of SR diesel and FCC diesel was commercially applied in a 3.6 Mt/a kerosene-diesel medium-pressure hydrocracking unit of CNOOC Huizhou Petrochemical Company. The catalyst has been running for 8 and half years without changing the structure of the device. However, even the mixing ratio is up to 21%（w），the device ran smoothly in such conditions，the comprehensive energy consumption increased from 777.121 MJ/t to 952.315 MJ/t. The qualities of heavy naphtha, jet fuel and diesel products are all on spec. Compared with the kerosene-diesel feed case, the yield of jet fuel decreased by 11.99 percentage points，and the smoke point decreased by 4.6 mm，the density（20 ℃）was increased by 12.8 kg/ m3 and the volume percent of the aromatic was increased by 8 percentage points；the cetane number of the diesel is 16.4 higher than the blending feed itself, but 5.5 lower than the diesel before blending，while the yield increased by 8.29 percentage points. The technology raises the volume of China V diesel, satisfy the need of the Company and provide a new way for the large refinery to optimize the material balance.

Key words: medium pressure hydrocracking, FCC diesel, blend, product quality, energy consumption