The hydrodynamics in circulating fluidized bed (CFB) are complex. In spite of increasing interest in CFB fundamental research in the past decades, the knowledge on the hydrodynamics is still not sufficient for straightforward design control and scale-up of CFB . In this work the non-linear analysis technique (chaos and fractal theory) combining with the new mathematics tool (wavelet transform) is applied to analyze the solid hold-up and pressure fluctuation signals in CFB riser for understanding the complex...