Abstract: The main features and process flow of a 1.2Mt/a hydrocracking unit in Daqing Petrochemical Company are introduced. The hydrocracking catalyst PHC-03 developed by Petrochemical Research Institute, PetroChina has been applied in Daqing refinery. The whole start up process of the device is described in detail, including catalyst loading, drying, sulfidation and passivation. The main operation parameters, feedstocks and products properties, material balance, energy consumption and operation situation are introduced by the analysis of the calibration data. The application results show that the unit has run smoothly and the performance of PHC-03 catalyst is good and flexible to different feeds. Excellent product quality and rational distribution with good middle distillate selectivity are obtained and the catalyst can be used to produce 3#jet fuel.