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We reported a simple laser-induced Rayleight light scattering (LIRLS) for ultrasensitive detection of Hg2+ and K+ ions based on the use of aptamer as a recognition element and gold nanoparticle as a reported element.Because laser-induced light scattering of the AuNPs increased with increasing the particle size,aggregated AuNPs exhibited relatively strong Rayleight scattering relative to dispersed AuNPs.Based on thais concept,LIRLS is a suitable strategy to combine salt-induced gold nanoparticle sensor.We utilized the 488 or532 nm laser to excite directly the cuvette containing gold nanoparticle and collected Rayleight scattering signal by the portable spectrometer which placed in 90°to isolate the intense laser beam and Rayleight scattering signal.We modified the gold nanoparticles with polythymine oligonucleotides T33 for selective detection Hg2+ ions and K+ aptamer (GGG TTA GGG TTA GGG TTA GGG) for selective detection K+ ions.Gold nanoparticles adsorbed on randomly oligonucleotides were dispersed well in PBS because of strong electrostatic repulsion between DNA molecules.The formation of T-Hg2+-T with Hg2+ ions and four-stranded tetraplex structure (G-quartet) complexes with K+ ions enabled the removal of oligonucleotides from the gold nanoparticles surface,resulting in salt-induced gold nanoparticles aggregation.The average diameter of aggregated gold nanoparticle increased linearly with the concentration of targets.Under optimum conditions,the average diameter of above modified nanoparticle increased linearly with the target Hg2+ concentration over the range from 0.1 nM to 100 nM,with a detection limit of 0.05 nM and K+ concentration ranging from 50 μM to 10 mM,with a detection limit of 1 μM.The result shows that the combination of salt-induced gold nanoparticle aggregation and laser-induced rayleight light scattering method has great potential in the analysis of interesting analyst.