In batch cultures,the effect of Ca^2+ and Mg^2+ on the denitrifying degradation properties of quinoline was investigated.The results show that Ca^2+ and Mg^2+ significantly promoted the denitrification degradation of quinoline and the optimum Ca^2+ and Mg^2+ concentration was 100 mg/L.The promotion effect was obvious at low concentrations and decreased at high concentrations.Ca^2+ and Mg^2+ significantly promoted the conversion of NO3^--N,and the conversion rate was higher when the concentration was 7~100 mg/L.While the change of pH was different under different Ca^2+ and Mg^2+ concentrations during the process of reaction,the final pH was stable at about 7.5,which was suitable for the growth of microorganisms.Appropriate amounts of Ca^2+ and Mg^2+ had the effect of promoting microbial growth and flocculation.The research results have practical guiding significance for the biological treatment of quinoline wastewater.