Abstract: A selective and efficient precipitant of gold, silver ions from thiourea leaching solution was proposed. And the effects of factors such as thiourea concentration, metal cation initial concentration, pH value and the additive quantity of precipitant anion on the precipitation rate of gold, silver and other metal cation and precipitant anion in thiourea leaching solution were investigated. A formula based on the sedimentation rate of ions changes in the solution with sediment formation, was used to calculate the precipitation rate. Reactions of this precipitant and metal cations such as gold, silver, copper, lead, iron (II), iron (III) and thiourea were used to verify little effect of other metal cations on the extraction of gold and silver of this precipitant in acidic solution and the effectiveness of this calculation formula.