Nanoparticles (NPs) such as Ag NPs, Au NPs, and bimetallic Au/Ag nanoalloy are of great interest for a range of applications in fields ranging from plasmonics to catalysis.In this work, plasma-assisted electrochemistry was applied to produce crystalline Ag NPs, well-mixed Au/Ag nanoalloy in electrolyte, and the in situ monitoring of NPs growth was incorporated into the experimental set-up, which affords a real-time information about the synthesized NPs, and capability essential for quality control of nanomaterial production.by synthesizing Ag NPs, pH value, conductivity and temperature of the eletrolyte were studied as a function of the micro-plasma current, processing time and concentration of AgNO3, and the way to control the size and size distribution of Ag NPs was discussed.By synthesizing Au/Ag nanoalloy, a novel approach was put forward to produce Au/Ag nanoalloy in absence of the harmful reducing agents such as NaBH4 needed for conventional colloidal chemistry method.