Abstract: Objective To analyze the combined toxicity of three typical pollutants，including cyanogen（CN^-），mercury（Hg²⁺） and glyphosate，in water environment to marine luminescent bacteria. Methods The different concentrations of CN^-，Hg²⁺ and glyphosate were combined on pairwise mode in equal volumes to form a mixed solution. At the same time，3% NaCl solution was used as the blank control，and Photobacterium phosphoreum T3 variant was added. The luminosity of the samples and the blank control were tested with a biological toxicity tester，to calculate the luminescent loss rate，and the data were analyzed. Results There was statistically significant difference in the luminous loss rate caused by the combination of CN^- and Hg²⁺ at different concentrations（P<0.01）. The combination of CN^- and Hg²⁺ at the concentration of median effective concentration（EC₅₀），which reduced the luminescent rate of Photobacterium phosphoreum by 50%，resulted in the highest luminescent loss rate of （84.00±16.74）%. For the combinations of CN^- and glyphosate or Hg²⁺ and glyphosate，it also showed a similar trend（all P<0.01）. The luminous loss rate caused by the combination of CN^- and glyphosate at the concentration of EC₅₀ was （81.07±17.22）%，and the luminous loss rate caused by the combination of Hg²⁺ and glyphosate at the concentration of EC₅₀ was （82.47±19.73）%. Conclusions With the increase of the concentration of combined pollutants，the luminous loss rate also gradually increases. The luminous loss rate caused by the mixture of the two pollutants is greater than that caused by the two pollutants alone. Using marine luminescent bacteria to monitor and evaluate the toxicity of combined pollutants in water environment has certain advantages.

Key words: Environmental pollutants, Combined toxic effects, Luminescent bacteria