Abstract: Radial friction is one of the common faults during the operation of centrifugal compressor set, and the extra heat generated thereby may result in the thermal bending of rotor, which has complicated impact on the rotor vibration. In order to accurately identify and diagnose this fault, an analysis model for rotor vibration was established. Meanwhile, the changes in phase lag, unbalance and vibration response of rotor at thermal bending caused by the radial friction between the rotor and stator were analyzed, and on this basis, the effects of different levels of thermal bending caused by radial friction on the vibration of rotor were studied. The results show that: when thermal bending is caused by the radial friction, the vibration response of rotor will produce a series of regular changes due to the change in phase lag and unbalance of rotor. Moreover, the relevant theories were verified by example application, thus providing theoretical and practical support for the fault diagnosis and analysis. Generally, the research results are helpful for the field operators to identify the thermal bending caused by radial friction, predict the fault location, find out the fault reasons, evaluate the fault severity and prepare the maintenance plan, so as to provide a powerful guarantee for the safe operation of centrifugal compressor sets which are applied to long-distance natural gas pipelines.