Abstract: The brewery wastewater is treated by aeration in the fluidized-bed bioreactors with immobilized cells.The influence of the bioreactor with internal cycle and without internal cycle on the efficiency of treating wastewater are compared,the efficiency can be remarkably improved with the interanl cycle.The stability of bioreactor for treating the wastewater is investigated,and the concept of stable constant α and property index δ are proposed through treating the wastewater continuously to estimate the bioreactor.