Using ascorbic acid as reducing agent and gelatin as dispersant, the spherical ultra-fine silver powder was synthesized by the chemical reduction method. The influence of AgNO3 solution concentration, pH value, gelatin dosage and reagents adding orders on the diameter of silver particles and particle distribution were studied. The spherical ultra-fine silver powder with the diameter of about 1.5 μm and homogeneous particle size distribution is prepared under the conditions as following: adding 0.5 mol/L AgNO3 solution into 0.25 mol/L ascorbic acid solution, gelatin dosage 1.5% of AgNO3 mass, adding gelatin drop by drop after the precipitate appearing, and pH=7.