Pressure fluctuations of fluidized beds have been used to evaluate the fluidization quality. In bubbling fluidized beds, the bed behavior is characterized by bubbling. The information indicated by the pressure fluctuation signals can be applied to describe those behaviors. The signals representing the characteristics of bubbling can be separated from original signals through discrete Wavelet analysis. Considering the principles of Wavelet, the Scale 4 detail signals can reveal the bubble behaviors in a fluidized bed. The peak frequency of the Scale 4 detail signal stands for the bubbling frequency and the peak amplitude for the bubble size.