Dynamic phase tracking method was proposed by using the instantaneous local solids concentration signals to demarcate the regime transition from bubbling to turbulent fluidization. Compared with the conventional methods, this method can provide clear demarcation between bubbling fluidization, the transition process and turbulent fluidization. And some detailed characteristics about regime transition had been obtained. The tendency of bubble coalescence surpasses that of bubble breakup in bubbling fluidization, but the latter one is the primary phenomenon in turbulent fluidization. And in the transition process, neither of the tendencies is dominant. Moreover, the transition process is increasingly gradual, with radial position extending from the center to the wall region, with axial position moving from the top to the bottom of the fluidized bed, and with static bed height becoming higher. Whether the transition process is more gradual is positively correlated with the solids concentration of dense phase. (C) 2019 Published by Elsevier B.V.