The influence of distributor structure on solids distribution is studied in two riser circulating fluidized bed reactors with different distributor structures but similar diameters. Optic fibre probes were used for the measurement of local solids distribution. The axial and radial distribution of solids holdup in the riser with a multi-tube distributor is more uniform than that with a multi-orifice distributor. The radial profiles of particle velocity in the riser with the multi-tube distributor are also more uniform than that with the multi-orifice distributor. In the riser with the multi-tube distributor, both gas and particles are distributed more uniformly across the section, so that the flow acceleration is much more uniform and faster. The flow development is much faster and the fully developed region is reached early for the riser with the multi-tube distributor. The distributor design is an important factor for the design of circulating fluidized bed reactor.