A novel method for the determination of trace lead in Yellow River using ammonium molybdate (AM) as a molecular probe based on resonance light scattering (RLS) has been developed. In the presence of KHC8H4O4–NaOH buffer solution, Pb2+ can react with AM to form an association, which results in the significant enhancement of RLS intensity and the appearance of the corresponding RLS characteristics. The enhanced RLS intensity is directly proportional to the concentration of Pb2+ in the range of 0.01–1.0μgmL−1. The detection limit can achieve 1.89ngmL−1. Moreover, the characteristics of RLS spectra of the complexes, the optimum conditions and the influencing factors have been investigated. The method has high selectivity and sensitivity, and was applied to the determination of Pb2+ in Yellow River with satisfactory results, which was in agreement with that of atomic absorbance spectrometry (AAS).