Abstract: A new method, measuring and analyzing pressure fluctuation signals of wind caps to monitor conditions of gas-solid flow in circulating fluidized beds, was proposed. The pressure fluctuation signals of the central wind cap, the differential pressure signals of adjoining pressure taps along the riser and solid circulation rates were measured at different primary air velocities in a cold circulating fluidized bed. To obtain the corresponding characteristic parameters, which reflect the effects of primary air velocity on the gas-solid fluidization characteristics of circulating fluidized beds, the pressure fluctuation signals in the wind cap were analyzed with the methods of wavelet analysis, homogeneous index and energy weighted average frequency. The mean solids holdups at various heights were calculated based on the differential pressure signals of adjoining pressure taps along the riser. Based on the characteristic parameters of wind cap pressure fluctuations, mean solids holdups at various heights and solid circulation rates, the effects of primary air velocity on the gas-solid fluidization characteristics were analyzed. It is found that the variations of characteristic parameters of wind cappressure fluctuations are related with the variations of the gas-solid flow condition caused by the primary air velocity change. It is proved that the proposed method is practical.