Abstract: The effects of Ca²⁺, Mg²⁺, and Zn²⁺ ions on the morphology of iron oxide red seeds produced by ammonium process were studied according to the situation in Zhongyuan Gold Smelter. It is shown that the presence of Ca²⁺, Mg²⁺ and Zn²⁺ ions has influence on the color, composition and morphology but their influencing degrees are different. The maximum concentrations influencing the seed quality are 0. 04g·L^-1 for Zn²⁺, 0. 25g·L^-1 for Mg²⁺, and 0. 1 g·L^-1 for Ca²⁺, respectively. The results also reveal that the treatment of tap water by adding ammonia water can eliminate the influences of Mg²⁺ and Ca²⁺ ions.