A salt-tolerant strain GYW capable of decolorating azo dye was isolated and identified as Halomonas sp. by 16S rDNA. The result showed that the decolorizing salt-tolerant bacteria could survive above the 10% salt concentration and it could decolorize many dyes. The strain had a high decolorizing rate on acid red GR under the condition of pH 7.5, anaerobic 30°C and 10% NaCl. The ion of Cl- strong inhibited the decolorization of acid red GR, and the ion of SO42- affected little on the decolorization, and the lycine addition with the optimal concentration of 200 mg/L could enhanced the decolorization rate under high NaCl concentration.