This paper is mainly aimed at studying the differentiation phenomenon of rare earth elements in the weathered crust elution-deposited rare earth ore. Through the study of the mineral characteristics and adsorption of kaolinite and halloysite-7Å, the authors simulated the process of adsorption of rare earth elements, and investigated the genesis of the deposit. According to the results of the experiments, the adsorption capacity of halloysite-7Å for rare earth elements is far greater than that of kaolinite. In addition, when the pH of the system is lower than the point of zero charge of the two minerals or there are metallic cations in the system, the adsorption capacities of both minerals are greatly affected. The results of lateral comparison experiments suggest that, regardless of the change of pH or the addition of Na⁺ in the system, kaolinite and halloysite-7Å will not show the characteristics of adsorption dissimilarity, and the adsorption patterns of rare earth elements are relatively similar. Only when K⁺ is inside the system, the adsorption patterns of both clay minerals for rare earth elements show divergence, of which MREE and HREE are mainly adsorbed by kaolinite while LREE are mainly adsorbed by alloysite-7Å. Therefore, K⁺ produced by weathering of rocks causes kaolinite and halloysite-7Å to exhibit selective adsorptions, which further affects the distribution of REE in the REE deposit.