The invention relates to a preparation method of spherical silver powder for a photovoltaic positive silver electrode. The spherical silver powder prepared through the method is high in dispersity, high in sphericity and high in tap density; the particle size ranges from 1-3 microns, and the spherical silver powder is subjected to narrow particle size distribution. The method comprises the steps of adding a thickening agent and a dispersing agent to a prepared silver-ammonia solution; controlling system temperature and adding a weak reductant to an ultrasonic water bath kettle; and reducing toobtain the high-dispersity and high-density spherical silver powder. The silver powder is used for preparing photovoltaic positive silver electrode sizing, and uniform silver-silicon contact is realized after sintering; and meanwhile, the silver powder is high in photoelectric conversion efficiency and stable electricity performance.