Abstract: This paper presents an experimental study on the radial and axial profiles of local particle velocity of flu-idized catalyst(FCC)particles in a circulating fluidized bed of 8000mm in height and 186mm in inside diameterwith a Fiber-Optic Probe Laser Doppler Velocimetry.It has been found that the radial profiles of local particlevelocity are parabolic,even in the centre region and steep in the region near the bed wall,and that the length ofparticle acceleration along the bed height is longer than expected.The following formula has been recommended to correlate the 1 ocal particle velocity with dilute gas-solidflow in the bed:where a,b,c and e are functions of radial positions.