Taguchi robust design method with L 9 orthogonal array was implemented to optimize experimental conditions for the preparation of nano-sized silver particles using chemical reduction method. Particle size and the particle size distribution of silver nano-particles were considered as the properties. Molar concentration ratio of R ([AgNO 3]/[reducing agent (hydrazine)]) value, concentration of dispersant (sodium dodecyle sulfate, SDS), and feed rate of reactant were chosen as main parameters. As a result of Taguchi analysis in this study, the concentration of dispersant was the most influencing parameter on the particle size and the size distribution. The feed rate of reactant had also principal effect on particle size distribution. The optimal conditions were determined by using Taguchi robust design method and nano-sized silver particles (∼8 nm) were synthesized. In addition, by the analyses of X-ray diffraction, high-resolution transmission electron microscopy, and electron diffraction (ED) pattern, the resultant particles were characterized to be pure crystalline silver with a face-centered cubic (fcc) structure.