The invention discloses a silver paste used for positive electrodes of solar batteries and grid lines, which comprises silver powder, glass powder, additive and an organic carrier. The silver paste is prepared by the following steps of: preparing a highly dispersed superfine silver grout used as the silver powder through a chemical liquid phase reduction method, then obtaining wet silver powder through solid-liquid separation, and preparing the agglomerate-free silver paste through direct mixing of the wet silver powder and the glass powder, the additive and the organic carrier according to the specified proportion without drying. The method for preparing the positive silver paste directly by using the wet silver powder comprises the steps of: preparation of the superfine silver powder through the chemical liquid phase reduction method, solid-liquid separation, washing, and direct preparation of the silver paste without a drying procedure in which the silver powder is easily agglomerated. The silver paste is characterized by high dispersity, no agglomeration and smaller fineness; and positive electrodes of solar batteries and grid lines, prepared through the screen printing and fast sintering process, have high definition, high evenness, high electrical conductivity and excellent photoelectric conversion efficiency.