Abstract: In order to improve the quality of FCC gasoline and increase the economic profit，SINOPEC Guangzhou Company, tried the hydrocracking of feedstock blending with coker gas oil. The results indicated that when processing the blending feed, the tail oil BMCI was increased and ethylene cracking furnace operation cycle was shortened. To solve these problems, we used KBC's Petro-SIM software to optimize the operation conditions of the hydrocracking unit. The optimized conditions are: hydrogen partial pressure of 13.31 MPa and the cut-point of fractionation tower of 375 ℃. After optimization, the tail oil BMCI decreases from 13.01 to 11.03, the cracking furnace coke cleaning cycle extend from 28 days to 52 days.