Stable concentrated ethanol dispersions of silver nanoparticles with a narrow size distribution were obtained at room temperature. The morphology and optical properties of the silver nanoparticles were characterized by transmission electron microscope (TEM) and visible spectrophotometer (UV-Vis). The results show that the silver particles possess spherical shape with an average diameter of about 4.8 nm with a good dispersion. During the preparation process, poly(vinyl pyrrolidone) (PVP) is used both as a reducing agent and a protecting agent and ethanol is used as a solvent that could rapidly reduce Ag+ in favor of a positively optimum extension of PVP molecule chain which increases the contact chance between PVP and Ag+. Moreover, the PVP molecule of full extension could effectively avoid aggregation of silver nanoparticles