Local phase holdups in an inverse three-phase turbulent bed of 150 mm i.d. and 4350 mm height were measured simultaneously by micro-electrical conductivity probe technique in this study.The experiments were carried out with polyethylene particles （dp=4.01 mm, ρs=926 kg·m -3）,air, and water[0.05%（mass）SCMC, 0.20%（mass）SCMC] as solid phase,gas phase and liquid phase respectively.540 sets of experimental data of local phase holdups in radial direction were obtained under Ug=U g3. It was found that the distribution of local solid holdup showed a maximum peak at r/R=（0.75—0.90）. The range of maximum peaks was larger than that of conventional fluidized beds. The distribution of local gas holdup in radial direction showed a maximum value at the column center and a minimum value near the wall.Moreover,the non-homogeneous distribution of local gas holdup in radial directions was more evident than that of conventional fluidized beds.The different operation regimes as well as the corresponding three specific gas velocities （U g1 ,U g2 and U g3） were obtained on the basis of the axial distribution characteristics of cross-sectional average solid holdups.The effect of the operating conditions （liquid viscosity, initial volume fraction of solids H s0/H0, initial liquid height H l0 ） on the specific gas velocities was presented.
