A scalable approach for preparation of Ag nanoplates in one-step is reported. Well-defined Ag nanoplates were obtained by reducing silver nitrate with hydrazine hydrate in the presence of insoluble silver salt, such as AgSCN, AgCl, AgEr, AgI, Ag2CO3, Ag2SO3, and Ag2C2O4. The size of Ag nanoplates can be well controlled by simply adjusting the ratio of Ag seeds to the amount of AgNO3. The exclusive formation of Ag nanoplates was due to the homogeneous nucleation of Ag nanoparticles is avoided in the presence of a small amount of counterions of insoluble silver salts, and large-scale synthesis with a yield ca.75 times higher than the record was achieved. In addition, a detecting strategy toward oxidizing substances in aqueous solutions was summarized based on the change of the surface plasma absorption via the size variation of the Ag nanoplates. This detecting method combines the advantages of generality, rapidity, simplicity, as well as a low detection limit and a wide linear response range. (C) 2015 Elsevier B.V. All rights reserved.