This paper introduces the abnormal phenomenon of liquid entrainment in the suction line of cracked gas compressor in the 1100 kt/a ethylene plant at PetroChina Dushanzi Petrochemical Company, analyzes the causes of the problem from various aspects, and puts forward some specific measures for alleviating the liquid entrainment in the suction line of cracked gas compressor. The analysis results show that the root cause of the liquid entrainment in suction line of cracked gas compressor and the abnormal formation of grease in caustic wash tower is the serious blockage of demisters for the interstage tank of cracked gas compressor and the knockout drum at inlet of caustic wash tower, which resulted in a decrease in demisting efficiency and then the liquid entrainment in suction line of compressor. Therefore, the demister for the interstage tank of cracked gas compressor was replaced as a whole, fundamentally solving such problems as the liquid entrainment in suction line of compressor and the abnormal phenomenon in caustic wash.