Nitrate contaminated water can be effectively treated by heterotrophic, mixotrophic and autotrophic denitrification. In this study, an newly anaerobic denitrifying bacterium, A14, with high denitrification and Mn(II) oxidation ability was isolated from sediments. And evaluating the performance of denitrification in autotrophic, mixotrophic and heterotrophic medium. The removal rates of nitrate were 0.301 mg.L-1.h(-1) (heterotrophic), 0.174 mg.L-1.h(-1) (mixotrophic) and 0.138 mg.L-1.h(-1) (autotrophic), respectively. Meteorological chromatography analysis showed that N-2 was produced as an end product. And the characteristics of gas composition were different in the various medium. Sequence amplification identified the presence of the cumA gene, which has been reported to be responsible for the Mn(II) oxidation. And XRD, SEM analysis suggest that MnO2 as an end product for the Mn(II) oxidation.