The unbalance in rotating machines is one of the major sources of rotor damage. Therefore, providing information on the behaviours of the unbalance rotor shaft is necessary to avoid the early damage of the rotor shafts and improve the efficiency of the rotating machines. For this purpose, the dynamic behaviour of a rotating composite hollow shaft is investigated by analyzing the vibration of a homogenized finite element beam model contain a flexible composite hollow shaft and a solid disc through identifying the relationship between the rotor unbalance response with both magnitudes of the imbalance and the rotating speed of the rotor as a function of frequency response. The Campbell diagram and stability analysis of the composite shaft is investigated.