During normal operation of the cracking gas compressor in the ethylene plant of PetroChina Liaoyang Petrochemical Company, abnormal vibration of turbine occurred many times, seriously affecting the safe operation of compressor unit. The factors influencing the process and equipment were investigated and analyzed comprehensively, the steam turbine was disassembled for repair, and the main factors causing the vibration of turbine were identified. The vibration of turbine was eliminated by taking corresponding treatment measures.