Gas-solid-solid circulating fluidized bed is a novel gas-solid contactor which offers interesting heat and mass transfer properties. In this type of equipment, large particles (often used as the catalyst) are fixed in the bed forming a packing section while fine powders (often used as the absorbent or heat carrier) are carried by the gas and flow through the packing. In this paper, the pressure gradient and powder hold-up in the packing have been measured in a rectangular fluidized bed. A theoretical analysis for the prediction of pressure drop, which is caused by the powder hold-up and the friction between gas and packing and between powders and packing, has been proposed. The predicted results agree well with the experimental results.