Aimed at the misdiagnosis shortage of rotating machinery pedestal looseness fault recognition, a new fault identification method based on dynamic characteristics of lubricating film is proposed to distinguish the pedestal looseness fault from the rotor′s misalignment, crack, rub. A single-span-single-disc rotor system with one end loose is selected as the research object, and the dynamic model of the single and pedestal looseness fault is established. According to the analysis of the thickness dynamic characteristics and the changing frequency spectrum of the lubrication film with rotational speed, the dynamic variation rule of sensitive lubrication film thickness when the pedestal is loose is obtained. The simulation and experimental results show that the recognition method can avoid the disadvantages of using rotor vibration information identification alone.