Using ascorbic acid (C6H8O6) as the reducing agent and AgNO3 as the source of Ag, the ultrafine silver powders were prepared by a liquid phase reduction method. By means of the orthogonal design method of six factors and five levels, the effects of the following factors on the dispersion and particles size of silver powders were studied, such as the concentration of AgNO3, the concentration of C6H8O6, the selection of dispersers, the doses of disperser, pH and the temperature. The optimized conditions for the ultrafine silver powders preparation were obtained. The pure ultrafine silver powders with near-spherical shape and mean diameter of 0.89 μm can be synthesized under the conditions of AgNO3 concentration of 0.15 mol·L-1, C6H8O6 concentration of 0.40 mol·L-1, oleic acid (C18H34O2) as disperser, C18H34O2/AgNO3 mass ratio of 8:100, pH=4 and at 50 oC. The ultrafine silver powders were characterized by scanning electron microscopy (SEM) and XRD