The invention discloses a method for treating waste lead paste by an Ausmelt furnace. The method comprises the following steps: the waste lead paste, iron powder and limestone are granulated; and the oxidation and reduction reactions are performed in the Ausmelt furnace to obtain lead bullion and waste slag. The method finishes the oxidation and reduction reactions of the waste lead paste in the Ausmelt furnace to directly prepare the lead bullion, effectively shortens the technological process, realizes one-step lead smelting, saves the equipment investment, and effectively reduces the cost. The method enables the lead content of the slag to be lower than 2% and to be far lower than the average lead content of higher than 3.5% in the waste slag in a traditional smelting technology, can effectively increase the direct lead yield, and reduces the lead content in the slag and the cost.