Cracking gas compressor, ethylene refrigeration compressor and propylene refrigeration compressor are the core equipment of ethylene plant, and their high-efficiency operation is extremely important to the safe, stable, long-term, full-load and optimum operation of ethylene plant. This article focuses on the problems that occurred during the maintenance of three key compressors in the 1000 kt/a Ethylene Plant of PetroChina Dushanzi Petrochemical Company, and analyzes the root causes of the impeller erosion, coking and gas seal corrosion in the high pressure cylinder of cracking gas compressor based on process operation data. At the same time, in view of the leakage of extraction flange of cracking gas compressor, the detached spool of high pressure valve of ethylene and propylene refrigeration turbines and the air leakage of valve stem packing, some maintenance control methods and countermeasures are proposed.