Abstract: Abstract: Based on geochemical research, we analysis the weathering crust of ionadsorption type REE deposit in Huidong area, Guangdong. The data show that the content of CaO,Na2O and K2O are decreased with the increase of weathering, Al2O3 is opposite. The trace elements such as Ba,Sr,U and REE are enriched in the semiweathered layer and weathered layer. The characteristics of distribution and content of the elements in weathering crust profile reflect the nature of parent granite. The index of WIG is more effectively to describe the weathering degree of the profile than CIA. The degree of weathering and enrichment of REE decrease with the increase of WIG. It can be concluded that LREE are abundant in upper of weathering layer ,while HREE are abundant in semiweathered layer and in lower part of the weathered layer. Eu and Ce are significantly loss in area where enrichment of the REE.

Key words: ionadsorption type REE deposit, geochemical characteristics, degree of chemical weathering, coefficient of elements migration, Huidong area, Guangdong