Abstract: Fluidization under the action of external forces has recently received much attention at home and abroad.Funda-mental study in this novel field has led to the creation of new techniques and equipment in chemical and biochemical pro-cesses,such as reactors for catalytic and pseudo liquid-solid reactions as well as contaetors for gas-liquid-solid systems.In conventional fluidization,solid particles acquire fluidity under the action of a gas or liquid passing at a sufficientvelocity.Under the action of external forces,fluidization can take place at fluid velocities higher than that for particleelutriation or lower than that for incipient fluidization under normal conditions.These external forces can often help toavoid bubbling or suppress backmixing,thus improving mass and heat transfer.Studies on fluidization under various ex-ternal force fields,such as magnetic,oscillating,centrifugal,and ultrasonic,will be reported in a series of papers.