Abstract: Beams with variable cross-sections show excellent mechanical properties, such as equal intensity, the optimization of mass distribution, and it has been widely used in bridge engineering. In the study, control equations of system vibration according to two types of boundary conditions (both of the two ends of the beam are clamped, one end of the beam is simply supported and the other is elastically supported) were given to study the dynamic responses of beams with variable cross-sections under move loads. Furthermore, the comparatively precise theoretical solutions were verified by the finite difference method. The result shows that the solutions are well consistent with that of the finite difference method.