Biological filtering is the core technology in maintaining the regular running of the high density of factory aquaculture.The well running filter will be effective in nitrification,which will be affected by different working parameters.Although there are some reports on biological filtering,all lack the research on the practical system directly.In this paper,the water treatment rates of floating bead biological filter under different conditions are compared.The results indicated that:(1) Without aeration,the nitrification efficiency of the floating bead biological filter is increased along with the reducing of the water influent;The removal rates of NH_4-N and NO~-_2-N are increased from 15.87% and 23.84% at 8 m~3/h influent to 38.85% and 71.37% at 2 m~3/h influent respectively;The best removal rate of COD is 10.33% when the influent reaches 4 m~3/h;Additionally,without aeration,the DO and pH of the outlet water from floating bead biological filter all have a little decrease.(2) Under the conditions with aeration,the water treatment efficiency also increased along with the reducing of the water influent;The removal rate of NH_4-N and NO~-_2-N are increased respectively from 6.45% and 51.45% at 8 m~3/h influent to 32.67% and 93.36% at 2 m~3/h influent;The best removal rate of COD reaches 12.20% when the influent is 4 m~3/h;The DO and pH of outlet water from the filter have some increase under these conditions with aeration.(3) The comparison of the conditions without aeration to the conditions with aeration indicates that the water treatment efficiency under conditions with aeration is superior to that without aeration.(4) The comparison of the water treatment efficiency under all conditions shows that the 6 m~3/h influent with aeration is the optimum working condition for fish cultivation.