Abstract: Roughing method to obtain symbol series of time series is refined in this research. Pressure fluctuation time series under various operating conditions, such as different flow regimes, static bed heights and average particle diameters, are analyzed in various scales through algorithm complexity for the first time. The result indicates that different trends of algorithm complexity in different scales correspond to the dynamic characteristics in fluidized bed. Algorithm Complexity C ( n ) is an explicit indicator of different fluidization regimes and different scales are distinct expressions of different fluidized phases. The larger scales are sensitive to bubble phase, and the smaller scales are sensitive to milk phase. Therefore, it reflects the dynamics of fluidized beds in various dimensions and gives more information than that of single scale. It is a new method for nonlinear analysis of pressure fluctuation time series.