Abstract: The hydrodynamics of a liquid - solid circulating fluidized bed was investigated in a plexiglass equipment of 140 mm in inner diameter and 3 m in height. In the circulating fluidizing regime, the bed has the characteristics of uniform distribution of phase holdups in the axial direction but non - uniform in the radial position. The solid circulating rate keeps constant when the superfacial liquid velocity changes within the circulating fluidization regime. Because of the non-uniformity of the phase holdups in the radial position there is a great difference between the theoretical results based on the generalized fluidization principles and the experimental results of the variation of the solid circulating rate versus the bed voidage.