In order to enhance the detection sensitivity of laser-induced breakdown spectroscopy ( LIBS),the effects of different kinds of halogen ions with different concentrations on the LIBS signal enhancement were studied.Suitable-sized silver nanoparticles were selected based on experimental conditions and absorption spectrum information.The amphiphilic molecule sodium dodecyl sulfate (SDS) provided the necessary viscous force,while halogen ions were introduced into silicon wafers as substrates to induce aggregation of the silver sol nanoparticles.The results show that halide ions induce nanoparticle aggregation and enhance LIBS emission intensities of Mg Ⅰ lines at the wavelengths 382.9 nm,383.2 nm and 383.8 nm.The limit of detection of Mg has been improved to μg/L.Effects of different halogen ions on nanoparticle enhanced LIBS (NELIBS) signal enhancement: F->Cl->Br->I-.The achievements of this study demonstrate that halide ions induced nanoparticle aggregation enhanced NELIBS signal and can realize the element detection and analysis of Mg in liquid,which meets new requirements of modern analysis technology.