Three-phase fluidized beds have been widely adopted in chemical and biochemical processing. To rationally design such fluidized beds, it is highly desirable that their complex hydrodynamic characteristics be thoroughly understood. A three-phase fluidized bed comprises two dispersed phases, one consisting of bubbles and the other consisting of fluidized particles, and one continuous phase, consisting of is a liquid medium. Since these phases interact among themselves in an intricate manner, the flow through the bed appears to be random and varies with flow conditions or regimes, thereby giving rise to various patterns of pressure fluctuations in different flow regimes. Such pressure-fluctuation flow patterns were analyzed by the wavelet transform, specifically, by the Coifman wavelet. The results of the transform visualize that the bubble coalescence occurs along the fluidized bed. Moreover, the return map based on the modulus by the wavelet transform illustrates the characteristics of generation of bubbles near the distributor.