The ethylene cracking furnace in the 1,000 kt/a ethylene plant at PetroChina Dushanzi Petrochemical Company was designed to use dimethyl disulfide (DMDS) to inhibit the catalytic reactions in furnace tubes, but the coking in furnace tubes could not be slowed down. The operation cycle of gas phase light hydrocarbon furnace was generally around 55 days, affecting the ethylene capacity of the plant. A coking inhibitor was used. It can be decomposed at 400 ℃, has lower decomposition temperature than other organic sulfides, is easy to play the anti-coking function, and has the advantages of low flash point and high boiling point. After the application of this coking inhibitor, the amount of coking was significantly reduced, the surface temperature of furnace tube was significantly decreased, the absolute pressure ratio and outlet temperature of quenching heat exchanger grew slowly, and the operation cycle of light hydrocarbon furnace was greatly prolonged. It also helps slow down the carburization of furnace tube and extend the service life of furnace tube.