A single particle inductively coupled plasma mass spectrometric(SP-ICP-MS) method was developed for simultaneous determination of the particle concentration,mass concentration and particle size distribution of nano silver particles(AgNPs) in environmental water samples.Effects of pH,dissolved organic matter(DOM) concentration and ionic strength of the solution on AgNPs were also investigated.A 60 nm AgNPs standard solution was determined by SP-ICP-MS with good accuracy,which results were consistent with the certified values.Impacts on the determine results were low in the conditions of pH value within 5 to 7,ionic strength not more than mmol/L and DOM concentration not larger than 30 mg/L.When pH value of the solution was not more than 5 or the ionic strength was larger than 1,the particle concentration and the particle size decreased with decreasing pH or increasing ionic strength.The method was applied to the detection of AgNPs in three actual water samples of river water,dye wastewater,and aquaculture wastewater,with the spiked recoveries for AgNPs of 98.1%,83.3% and 93.3%,respectively.Results indicated that the SP-ICP-MS method could be used for quick and accurate determination of the particle concentration,mass concentration,and particle size distribution of AgNPs in environmental water samples under appropriate matrix conditions.