Abstract: The rigid-flexible-thermal coupling dynamics of the hub-FGM beam system under large overall rotating motion is studied. The FGM beam is an Euler-Bernoulli beam, and its physical properties follow certain kinds of power law gradient distribution and vary in the thickness direction. The longitudinal deformation and the transverse deformation of the flexible beam are considered and the coupling term of the deformation which is caused by transverse deformation of the flexible beam is included in the expression of longitudinal deformation. Considering the influence of the thermal coupling of the tapered hollow beam which is under the condition of external high temperature and internal cooling passage cooling on the dynamic characteristics of the system, the temperature field distributed along the thickness direction of the FGM beam is obtained, and the thermal strain is included in the constitutive relationship of the beam. By using the assumed mode method to describe the deformation of the beam, the rigid-flexible-thermal coupling dynamic equations of the system are derived via employing Lagrange's equations of the second kind, as well as to compile the dynamics simulation software. Then the dynamics of the system are studied through simulation examples. The results show that the dynamic response of beams with different sections is quite different, so it is necessary to model the actual system reasonably. When the large overall rotating motion is known, the FGM beam considering the thermal shock load will effectively suppress the transverse bending deformation, and the high-frequency oscillation will occur with the superposition of the thermal shock when the large overall rotating motion is constant; When the large overall rotating motion is unknown, the external torque and the thermal shock load interact to produce a thermal coupling effect, which causes the system to exhibit high-frequency oscillation, at the same time , the rigid-flexible thermal coupling effect of the hub-FGM beam system is appeared.