Abstract: The method of reverberation-ray matrix （MRRM） is an efficient approach for analyzing the dynamic behavior of truss and frame structures. Due to its advantages of clearer physical interpretation and better numerical stability, this method has been extensively studied and employed by scholars. However, most existing studies of MRRM remain focused on the uniform elements, with limited consideration in the elements with variable cross-section. The main reason lies in the fact that, in the elements with variable cross-section, the phase relation in MRRM becomes difficult to be well established. In view of this, for a special kind of Euler-Bernoulli beam with variable cross-section, the corresponding MRRM formulation is derived in the present study for the problem of free vibrations. The natural frequencies and corresponding vibration modes of the beam are calculated based on this formulation, and the obtained results are efficiently verified by the finite element simulations.