To solve the dynamic problem for the out-of-plane vibrations of a rotating thin ring, this paper studied the basic transmission characteristics of elastic wave propagation, and analyzed the dispersion equation, wave numbers, cutoff frequencies, phase velocity and the ratio of axial vibration displacement to torsional vibration displacement, which is valuable in the free vibration analysis of the solid cage in a high speed roller bearing. Based on the wave propagation method, the positive and negative wave numbers were separated by the criterion of positivegoing waves. The characteristic equation of a rotating thin ring was established by the phaseclosed principle and the transfer matrices. One example was given to solve the natural frequencies of the rotating ring, and the result is consistent with the result of the given literature.