Abstract. Some areas have raised discharge standards for effluent total nitrogen (TN) concentration in China. However, the main component of effluent TN in the wastewater treatment plant is nitrate nitrogen (NO 3 --N). This research focuses on TN removal using deep-bed denitrification filter, the hydraulic retention time (HRT) and influent C/N ratio are optimized at 25 °C and 10 °C. The optimum influent C/N of denitrification filter is 3:1 at 25 °C and 10 °C. The optimum HRT is 0.25 h at 25 °C and 1 h at 10 °C. Under the optimum conditions, the average concentration of effluent TN is 6.76 mg/L at 25 °C and 8.76 mg/L at 10 °C. The minimum carbon source addition and shortest HRT of deep-bed denitrification filter at room and low temperature were optimized, which has a practical significance in environmental engineering.