In different beam models, the contribution of axial force to shear force varies, and this characteristic can be described by using transition parameter. This paper studies the influence of the transition parameter on the flap-wise bending vibration of Timoshenko beams when rotational effects induce axial centrifugal force. At the beginning of the study, the flap-wise bending vibration differential equations for the rotating Timoshenko beam were derived, which considered the transition parameter. In the following section, the differential equations were solved by using differential transformation method (DTM). At the same time, the natural frequencies and mode-shapes of system were obtained. In the end, the effects of transition parameter, rotating speed, cross section shape, and heighttolength ratio were discussed. The results show that transition parameter has an impact on the natural frequencies and mode-shapes of rotating Timoshenko beams, with a more significant effect observed at high rotating speed, thinwalled cross section, and large height-to-length ratio.