A continuously flowing, inner circulatory, quasi-fluidized-bed reactor for resin ion exchange and adsorption. The reactor comprises a main body casing, an inclined pipe separator, an outlet weir, an inlet pipe, an outlet pipe, a reducing fluidization tank, a guide plate, a resin regeneration tank, a resin discharge pipe, and a return pipe for regenerated resin and a distributing ejector. The reactor is particularly suitable for advanced treatment of supply water, wastewater, biochemical effluent and reclaimed water by using (magnetic) powder resin.