Pressure fluctuations in the riser of a circulating fluidized bed have been analyzed by means of stochastic analysis such as fractal analysis and phase space portrait, to analyze the characteristics of gas-solid contact and flow behavior in the riser. Polyethylene whose mean diameter is 0.454mm and density is 920㎏/㎥ has been used as a solid. The diameter and height of the riser are 0.102m and 3.5m, respectively. Effects of superficial gas velocity and solid circulation rate on the hydrodynamic characteristics such as solid interstitial velocity, slip velocity between gas and solid, and solid holdup have been determined. Effects of operating variables on the Hurst exponent and phase space portrait have been also examined. The values of the Hurst exponent have been recovered from the Pox diagram obtained by the rescaled range analysis of the data. The phase space portraits have been obtained by means of rearrangement of the data by the multidimensional phase space portrait method. As a result of this study, the concept of choking velocity is very similar to that of transportation velocity in the riser. The Hurst exponent has exhibited its maximum value and the phase space portrait has focused its tracing within the limited boundary at the transition regime of gas-solid flow.