Abstract: The single toxicity of three common heavy metals (Zn2+,Cu2+,Hg2+) and the joint toxicity of different concentration ratios to the gene recombinant luminescent bacteria (E. coli HB101 pUCD607) were analyzed, the toxic effects of the mixed system were evaluated using the Toxic Unit, Additional Index and Mixture Toxicity Index. The median effective concentration (EC50) of three heavy metals:Zn2+,Cu2+,Hg2+ was 4.16,6 and 0.98mg/L for 15 minutes, respectively. The mixed system of heavy metals mainly showedantagonistic effects in different degrees, the results of different evaluation methods of the three kinds of heavy metals have good consistency with each other. The joint toxicity of these heavy metals can provide reference for the control of heavy metal compound pollution and biological toxicity test.