Pressure fluctuations are often selected to analyze the dynamic changes in the gas-solid fluidized bed. In this study, the wavelet modulus maximum method is applied to analyze the pressure fluctuations in a circulating fluidized bed. Continuous wavelet transform is put on the pressure signals, then, maxima lines are extracted and the Lipschitz exponent, alpha, of every maximum line is calculated using the non-linear least-squares method. The mean of the negative alpha is adopted to describe the hydrodynamic characteristics in the circulating fluidized bed. The value of the mean of the negative alpha increases with the superficial gas velocity and turns stable when the flow regime is fast fluidization. This method has been tested effective under various operation conditions. (C) 2004 Elsevier Ltd. All rights reserved.