Abstract: As a new generation of antibacterial agent, silver nanoparticles are expected to be a substitute for traditional antibacterial agents in the future. Developing a new stable, efficient and eco-friendly nano-silver antibacterial agent has become the hot spot of current research. In this study, the grape seeds extract was used as an reducing and stabilizing agent, and polyvinyl alcohol (PVA) was used as the carrier, the silver nanoparticles/polyvinyl alcohol (AgNPs/PVA) composites were prepared by a facile, green, “one-pot” biological method. The asprepared AgNPs/PVA composites were characterized by UV absorption spectroscopy (UV-Vis), transmission electron transmission electron microscopy (TEM) and X ray diffraction (XRD). The results indicate that the silver ions are successfully reduced by the grade seeds extract and the produced AgNPs are decorated on the surface of PVA. The AgNPs are uniform and monodisperse, the particle size is small with mean diameter about 14 nm. The AgNPs/PVA composites show superior antibacterial effects against six tipical aquatic pathogens, such as Vibrio splendidus, V. harveyi, V. anguillarum, V. alginolyticus, V. parahaemolyticus and Aeromonas punctata. They have a minimum inhibitory concentration (MIC) of 1.1 μg/mL and a minimum inhibitory concentration (MBC) of 2.2 μg/mL against V. alginolyticus. The Zeta potential of AgNPs/PVA is found to be −24.1 mV, indicating that the strong repulsion between the nanoparticles, which provide guarantee for stable dispersion. The subsequent experiments prove that the prepared AgNPs/PVA has good stability and thermostability. The above research results indicate that AgNPs/PVA composites have a great application prospect in the control of aquaculture diseases.