Abstract: A new method of determining the critical transition point from bubbling to stabilized fluidized bed is presented in this paper. By measuring the void fluctuation in the bed with a capacitance probe and treating the measured data with stochastic method, the curves of dominant frequency Fd of void fluctuation vs magnetic intensity, H can be obtained. The extreme point in the Fd-H curve, i. e Fd reaches a maximum, corresponds to the critical transition point from bubbling to stabilized fluidized bed. The experimental results show that the critical transition point determined by this method corresponds well with that proposed by Rosensweigs transition rule.