Based on the principle of chemical reaction engineering,the addition of perforated plates can improve the performance of conventional bubble column and decrease the backmixing behaviors.The distribution characteristics of gas holdup in a multi-stage bubble column embedded with five types of sieve plates and three types of tongue plates were studied using electrical resistance tomography(ERT).The effects of superficial gas velocity and the geometric design of perforated plates on the gas holdup and its radial distribution above and below the plates of the bubble column were discussed.Experimental results show ERT is suitable as an online monitoring tool to provide useful information on the hydrodynamic parameters of multi-stage bubble columns.With increasing superficial gas velocity,local gas holdup increases,and gas holdup below the plate increases with decrease of free area(%FA),hole diameters or angle of tongue plates.ERT technique facilitates noninvasive and nonintrusive visualization of cross-sectional distribution of gas holdup in a bubble column. Based on the principle of chemical reaction engineering, the addition of perforated plates can improve the performance of conventional bubble column and decrease the backmixing behaviors. The distribution characteristics of gas holdup in a multi-stage bubble column embedded with five types of sieve plates and three types of tongue plates were studied using electrical resistance tomography (ERT). The effects of superficial gas velocity and the geometric design of perforated plates on the gas holdup and its radial distribution above and below the plates of the bubble column were discussed. Experimental results show ERT is suitable as an online monitoring tool to provide useful information on the hydrodynamic parameters of multi-stage bubble columns. Increasing superficial gas velocity, local gas holdup increases, and gas holdup below the plate increases with decrease of free area (% FA) , hole diameters or angle of tongue plates .ERT technique facilitates noninvasive and nonintrusive visualizati on of cross-sectional distribution of gas holdup in a bubble column.