An ecofriendly process has been successfully developed to synthesize the polycrystalline silver nanopolyhedrons with a high yield at large scale. By using tannic acid in the presence of poly (vinyl pyrrolidone) (PVP), high quality silver nanopolyhedrons were obtained in an aqueous one-pot reaction without any templates or auxiliaries. The film made from the silver nanostructures exhibits an electrical conductivity higher than 104 S/cm on both rigid and flexible substrates. The supreme mechanical strength of this silver film recommends its wide application in printing and flexible electronics.