A method for investigating the Corilois effect on the vibration of a cantilever plate rotating at a time-varying speed is presented in this paper. Due to this time-dependent speed, parametric instability occurs in the system. Furthermore, owing to the existence of the Coriolis force, the system equation is transformed, by a special modal analysis procedure, into independent sets of first-order simultaneous differential equations. This set of simultaneous differential equations is solved by the method of multiple scales, yielding the system response and the expressions for the boundaries of the unstable regions. Finally, the Coriolis effect on the changes in the boundaries of the unstable regions is investigated numerically.