Silver nanoparticles(AgNPs) are widely used antimicrobial compounds; however, they may pose a threat to non-targeted bacteria in the environment. In this study high-throughput sequencing was used to investigate the effects of different concentrations of AgNPs(10, 50, and 100 mg kg-1) on soil microbial community structure during short-term(7 d) exposure. The amounts of Acidobacteria,Actinobacteria, Cyanobacteria, and Nitrospirae significantly decreased with increasing AgNP concentration; meanwhile, several other phyla(e.g., Proteobacteria and Planctomycetes) increased and dominated. Nitrosomonas europaea, a well-characterized ammoniaoxidizing bacterium, was used to study the sensitivity of bacteria to Ag NPs and ionic silver(Ag~+). Flow cytometry was used to monitor the toxicity of low(1 mg L~(-1)), middle(10 mg L~(-1)), and high concentrations(20 mg L~(-1)) of AgNPs, as well as Ag~+(1 mg L~(-1)) released into the medium from 20 mg L~(-1) concentration of AgNPs, towards N. europaea. After 12 h of exposure, the survival rate of N. europaea treated with 1 mg L~(-1)Ag~+ was significantly lower than those treated with low(1 mg L~(-1)) and middle concentrations(10 mg L~(-1)) of AgNPs, but the survival rate in the treatment with high concentration(20 mg L~(-1)) of AgNPs was much lower. Additionally, necrosis rates were higher in the treatment with 20 mg L~(-1) AgNPs. Electron microscopy showed that Ag+caused serious damage to the cell wall of N. europaea, disintegrated the nucleoids, and condensed next to the cell membrane; however,dissolved Ag~+ is only one of the antibacterial mechanisms of AgNPs. In this study high-throughput sequencing was used to investigate the effects of different concentrations of AgNPs (10, 50, The amounts of Acidobacteria, Actinobacteria, Cyanobacteria, and Nitrospirae significantly decreased with increasing AgNP concentration; meanwhile, several other phyla (eg, Proteobacteria and 100 mg kg-1) on soil microbial community structure during short- Nitrogenomonas europaea, a well-characterized ammoniaoxidizing bacterium, was used to study the sensitivity of bacteria to Ag NPs and ionic silver (Ag ~ +). Flow cytometry was used to monitor the toxicity of low (1 mg L (-1 mg / L), middle (10 mg L -1), and high concentrations (20 mg L -1) of AgNPs, ) released into the medium from 20 mg L -1 concentration of AgNPs, towards N. europaea. Aft er 12 h of exposure, the survival rate of N. europaea treated with 1 mg L -1 Ag ~ + was significantly lower than those treated with low (1 mg L -1) and middle concentrations (10 mg L ~ (-1)) of AgNPs, but the survival rate in the treatment with high concentration (20 mg L -1) of AgNPs was much lower. Additionally, necrosis rates were higher in the treatment with 20 mg L ~ (-1) AgNPs. Electron microscopy showed that Ag + caused serious damage to the cell wall of N. europaea, disintegrated the nucleoids, and condensed next to the cell membrane; however, dissolved Ag ~ + is only one of the antibacterial mechanisms of AgNPs.