In this work, we report on silver nanocubes with perfect shape prepared by a simple poly(vinyl pyrrolidone)-directed polyol synthesis process. The effects of poly(vinyl pyrrolidone)/AgNO3ratio Rand reaction temperature Ton the morphology and size of the products were investigated. Ag nanocubes with an average edge length of 230 nm were obtained successfully with sharp edges and corners under a precise synthesis condition of R= 1 and T= 150 °C. The optical properties of Ag nanocubes show an attractive plasma resonance red-shift with size in a wide spectra region. The growth mechanism of the Ag nanocubes is proposed to be thermodynamically and kinetically controlled.