In this paper, a simple Timoshenko beam theory (STBT) is proposed and a radiative energy transfer model (RETM) based on STBT theory is established. The appropriate rotational inertia of Timoshenko beam theory (TBT) is discussed and the effects of two forms of rotational inertia on the high frequency vibration of a transverse vibrating beam are evaluated. Based on elastic theory and wave propagation theory, it is found that when the frequency is higher than the critical frequency, there is a second spectrum in TBT theory, which has no obvious physical significance. On the other hand, the so-called slope inertia Bresse Timoshenko (SIBT) is neither consistent nor accurate when the wavelength of the vibrating beam is close to the height of the beam. The theory cannot be used for vibration analysis above the critical frequency. By numerical analysis of the surface, the simple Timoshenko theory established in this paper and the energy model of high frequency vibration are very direct and effective. The effectiveness and simplicity of this model are verified by comparing it with several beam theory wave propagation methods.