Abstract: In order to eliminate the environmental pollution caused by the residual leaching agent in the weathered crust elution-deposited rare earth ore, the adsorption and desorption characteristics of montmorillonite, kaolinite and illite on NH₄⁺ in the leaching agent of weathered crust elution-deposited rare earth ore are investigated, and concentration of ammonium ion is determined by Nessler colorimetric-spectrophotometry in this paper.The results show that adsorption isotherms of ammonium on the three clay minerals are a mono-layer sorption and fitted well to Langmuir model.Maximum adsorption capacity of montmorillonite, kaolinite and illite on NH₄⁺ is 5.99 mg/g, 0.12 mg/g and 1.10 mg/g, and release source of NH₄⁺ is mainly from montmorillonite and illite.Desorption results show that efficiency of the eluate followed the order, Fe³⁺≈Al³⁺ ≥ Mg²⁺>Ca²⁺>K⁺>Na⁺>H₂O.Experimental results show that the NH₄⁺ desorption by magnesium salt is the fast process with high efficiency.Under the same conditions, the elution rate of residual NH₄⁺ in weathering crust eluvial rare earth ore is more than 95%.