Biological filtering is the core technology in maintaining the regular running of the high density of factory aquaculture.The proper 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 submerged biological filter under different conditions are compared.The results indicated that:(1) Without aeration,the best removal rate of NH4-N is 28.77% when the HRT is 18min.The removal rates of NO2-N is increased with the decreased water flow rates,which reach the top efficiency,67.20%,at the condition with 36 min HRT;The COD removal rate reaches the top at the condition with 36 min HRT,which is 6.65%.Additionally,the DO and pH of outlet water from the submerged biological filter at the conditions without aeration are lower obviously.(2) Under the conditions with aeration of 1 m3/h,the water treatment efficiency also increased with the reducing of the water influent.The removal rates of NH4-N and NO2-N are increased respectively from 7.54% and 49.30% at 9min HRT to 39.03% and 71.78% at 36 min HRT.The best removal rate of COD reaches 6.16% when the HRT is 36 min.And under these conditions,the DO and pH of outlet water have somewhat increased.(3) Under the conditions with aeration of 2 m3/h,the water treatment efficiency also increased with the decreased water flow rates.The best removal rate of NH4-N and NO2-N are 27.27% and 74.92% respectively which achieved at 36 min HRT.The removal rate of COD reaches the top when the HRT is 9min,which is 5.30%,and the DO and pH of outlet water also have some increase at these conditions with 2 m3/h aeration.(4) The results of comparison of the conditions without aeration to the conditions with aeration indicate that the water treatment efficiency under conditions with aeration is superior to that without aeration,and the treatment efficiency which achieved with 1 m3/h is relatively better than others.