Pyrolysis gas compressor is the most critical and important equipment of ethylene plant. This paper analyzes the causes of the abnormal vibration of high pressure cylinder in pyrolysis gas compressor, and uses status monitoring software and frequency and map analysis to determine that the root cause of vibration is the fluid-induced vibration caused by coking inside the cylinder. By taking some measures such as increasing the frequency of oil injection, extending the oil injection time, and optimizing and adjusting the amount of oil injection in each cylinder, the vibration of the compressor unit is eliminated, thus ensuring the normal and stable operation of the pyrolysis gas compressor.