The biological aerated filter (BAF) was used to treat the oil-field produced water. The removal efficiency for oil, COD, BOD and suspended solids (SS) was 76.3%-80.3%, 31.6%-57.9%, 86.3%-96.3% and 76.4%-82.7%, respectively when the hydraulic loading rates varied from 0.6m.h(-1) to 1.4m.h(-1). The greatest part of removal, for example more than 80% of COD removal, occurred on the top 100cm of the media in BAR The kinetic performance of BAF indicated that the relationship of BOD removal efficiency with the hydraulic loading rates in biological aerated filters could be described by c(r)/c(i) = 1-exp(-2.44/L-0.59). This equation could be used to predict the BOD removal efficiency at different hydraulic loading rates.