Based on the view about removal of sulfur by denitrifying，for which the bacteria was enriched in a continuous stirred reactor，and the functional bacteria was monitored and identified by plate count and PCR-DGGE methods. The single strain SNB1 obtained by isolation and purification of bacteria was also identified. In the reactor， the amount of bacteria for total，desulfurization and denitrifying increased by 1.92×10，6.49×105，1.66×103-fold. There are three dominant microorganisms in the reactor during stable operation. a，a flora and Thauera sp. homology up to 99.0%，and it is a kind of denitrifying bacteria. The physiological and biochemical characteristics of the SNB1 contained revealed that it is a kind of facultative autotrophic bacteria and has the 99.0% homology with Thauera selenatis. The ratio and amount of desulfurization bacteria are 49.3% and 3.70×109 cfu8226;ml-1.b，the homology of another flora with Desulfovibrio sp. is higher than 98%，it is sulphate-reducing bacteria. c，the homology of third flora with Rhodococcus sp. is higher than 94%，it is denitrifying bacteria. When S/N is in the range of 0.007—0.386，100% S2- and 46.47% SO2-4 are converted into S0. The removal efficiency of NO-3 and COD are 72.3%—95.8% and 9.8%—43.5%，respectively.