Abstract: In order to promote the application of functionally graded materials (FGMs) in the thermal protection systems of missile, the change laws of vibration modal for the thermal protection shell of a missile body under different variable quantity were studied. Firstly, based on the dynamic equation of a FGM shell, the thermal physical properties model of a FGM was employed to discuss the change law of the vibration modal of a FGMs shell with different ceramic volume fraction, thermal stress or thickness of missile body. Results indicate that the impacts of ceramic volume fraction on the modal shape of the missile body are unobvious; on the contrary it is very obvious to its vibration frequency. The change law of vibration frequency of the missile body is the results of interaction of thermal physics and thermal stress of the FGMs shell, the frequency increased by the increasing of thickness.