Abstract: In this paper the type "B" multi-stage fluidized bed for the gas-solid system has been studied. The apparatus used was a 180 mm. I. D. 3-stage bed. The first section of this paper deals with the working characteristics of the downcomer pipe. The influence of pressure drop through the distribution plate upon solid flow in the downcomer pipe has been examined. The authors suggest the use of reduced flow rate G/G0 and reduced pressure-drop gradient (P/L)/ (P/L)kp to correlate all the factors affecting solid flow. Data with the same value of d0/dT can be correlated satisfactorily with this method, but no simple relation seems to exist for data having different values of d0/dT. In the second section of this paper, a method of heat transfer calculation for the multi-stage fluidized bed has been proposed based on the assumption that the gas and solid leaving the fluidized bed are kept in thermal equilibrium. The equation derived is similar to the Kremsers[6,7] equation for absorption.