The nano-size silver particles were prepared in polymer-protecting colloidal dispersion with silver nitride as the raw material, hydrazine hydrate as the reduction reagent and polyvinyl pirrolidone (PVP) as the protective solvent. The optimal conditions for the preparation process were studied experimentally as well. The influences from main factors, such as Ag+ concentration and ratio of hydrazine/AgNO3, on the particle size, appearance shape, particle aggregation condition and size distribution of nano-silver particles were also investigated. The results showed that the size of Ag particles prepared in this polymer-protecting system is less than 50 nm, and PVP can reduce the growing tendency of nano-size silver particles. Meanwhile, the antibacterial dope loaded nano-silver particles were prepared by wetting agent, dispersant, defoamer, etc. The antibacterial and bacteriostatic effects of the dope with or without nano-silver particles were tested with bacilli as the tested bacteria. The experiment results showed that the dope loaded nano-silver particles are of high practicality. Its antibacterial ratio is also up to 91.9% in one hour when the added dosage of nano-silver is 0.02%.