In recent years, affected by the diversification of raw material to ethylene plant, the emulsification of quench water occurred. More and more benzene series remain in the system, leading to serious polymerization in process water system. The polymerization of process water not only leads to the blockage of multiple heat exchangers in the quench unit, but also may lead to the shutdown of the quench unit in severe cases, which becomes one of the main bottlenecks for the long-term operation of ethylene plant. A new reagent is used in the quench water system to improve the water quality and alleviate the emulsification and fouling problems of the water system, thus effectively prolonging the operation period of the ethylene plant.