According to the system resonance light scattering intensity will change with the variation of AgNPs aggregation state before and after the reaction,a novel resonance light scattering（RLS） method for the quantitative determination of trace hydrogen peroxide was developed using silver nanoparticles（AgNPs） as the resonance scattering probe.The silver nanoparticle with an average particle size of 4 nm was synthesized through the reduction of silver nitrate by sodium borohydride,using trisodiumcitrate as the protecting agent.The detection of H2O2 mechanism was based on that Mn2+ was chelated by the citrate covering on the surface of the silver nanoparticles, inducing the aggregation of AgNPs with increasing of resonance scattering intensity of the system.When H2O2 was added to the system,Mn2+ participated in Fenton-like reaction with H2O2 producing Mn3+ and hydroxyl radical（?OH）.The complexation reaction of citrate on the surface of the AgNPs with Mn3+ formed unstable complexes,and ?OH oxidatively etched AgNPs.Both of the two reactions could result in non-aggregation of AgNPs as well as relatively weakening resonance scattering intensity of the system. Under the optimal conditions,the resonance light scattering intensity of system at 411 nm was decreased linearly with concentration of H2O2 over the range of 7.88×10-8-1.418×10-5 mol/L,with a correlation coefficient of 0.9967 and a detection limit of 4.04×10-8 mol/L. This method was applied in the analysis of hydrogen peroxide in the lake and rain water samples with satisfactory results.