In order to reduce the energy consumption of the 220 kt/a ethylene plant in Dushanzi, it was proposed to change the operating mode of cracking furnace from 6 for operation and 1 standby to 5 for operation, 1 stopped and 1 standby based on the energy consumption analysis of the ethylene plant and the current working conditions of cracking furnace and cracking gas compressor. In order to select the optimal operating mode of 5 for operation, 1 stopped and 1 standby, the working conditions were tested in 5 stages. By comparing the design parameters of the No.2 gasoline fractionator (C-103), the relationship between the cracking gas load of the tower and the middle pumparound and gasoline reflux was optimized and adjusted, ensuring the stable and controlled quench oil viscosity and quench water quality. Through optimizing the operating mode of cracking furnace, the goal of energy saving and consumption reduction of the ethylene plant was quickly achieved.