Abstract: In order to improve the nitrogen removal efficiency and effluent quality of the threedimensional electrode biofilm process( 3BER),a new designed 3BER-NC process through expanding the area of electrode plate,reducing the electrode space and changing the electrode arrangement was applied and the effect of current,influent p H and ρ( C) / ρ( N) on the performance and denitrifying bacteria in system were studied in deep denitrification of the tail water from a municipal wastewater treatment plant.The research results showed that the 3BER-NC operated with an optimal current at 200 m A,which was100 m A higher than that of 3BER. Because of its shorter electrode space,the 3BER-NC can slow down the carbon electrolysis and effluent color. Furthermore,the enlargement of electrode plate and the change of electrode position distribution of the 3BER-NC improved the TN removal rate to 86. 45%,which was37. 74% higher than that of 3BER. The current intensity,influent p H and ρ( C) / ρ( N) had great influence on the nitrogen removal at different current and the nitrogen removal efficiency of 3BER-NC was better than 3BER. In the nitrogen removal system of the 3BER-NC,the β-proteobacteria played a leading role with a joint action of heterotrophic and autotrophic denitrifying bacteria.