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Micro-sized silver power was prepared from AgNO3 power by chemical reduction, and the technique was optimized by orthogonal experiment. The silver sol was obtained from silver nitrate via chemical reduction in ultrasonic wave and alkaline environment using polyethylene glycol (PEG-10000) as dispersant and alcohol as antifoam agent, and after agitation, the sol was filtered, washed and dried at constant temperature to obtain silver powder. Effects of reagents adding order, pH and dosage of alcohol on the silver particle size were investigated. The silver powders were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Results show that with 0.3 mol/L AgNO3 solution, 25 mL ethanol, T=40 oC, pH=7 and 10 min ultrasonic wave vibration, spherical silver power of about 1.13 mm particle size and narrow particle size distribution was prepared.