Abstract: Fault diagnosis method based on single parameter cannot judge the fault states of gas turbines accurately and efficiently, so the comprehensive diagnosis method based on vibration fault mechanism and performance fault mechanism was proposed. Abnormal vibration occured during the operation of LM2500+SAC gas turbine of the gas-driven centrifugal compressor set in one compressor station of the 1st West-to-East Gas Pipeline of PetroChina. In this paper, the condition monitoring data were analyzed according to the mechanisms of vibration fault and performance fault of gas turbine. Then, the factors inducing the abnormal vibration were checked one by one. And it is ultimately determined that the excitation source to the abnormal vibration of gas turbine is the unbalance caused by the damage of bearing rotating sealing. The serious consequence may be caused by the continuous operation of the failed compressor set was avoided. It is verified that the comprehensive diagnosis method is effective and it can be used as the reference for the monitoring and diagnosis of similar faults.