The Jianshui Puxiong rare earth deposit in southeast Yunnan is a super-large weathered crust ion adsorption rare earth deposit discovered and identified by the No.209 Geological Team，Geological Bureau of Yunnan Nuclear Industry. The ore body occurs in the fully weathered layer and semi-weathered layer of the Changlinggang alkaline rock body. The ore has high grade and large thickness which is different from the ion-adsorbed rare earth ore in the weathered granite crust； thus， conventional shallow wells and the Gannan drills cannot be used to expose the rare earth ore body. In this paper， the split tube core barrel and the construction of shallow wells in adjacent locations are used to compare the grade changes of the ore body in the Jianshui Puxiong mining area for the same sampling layer and sample length with calculation of the relative error， and positive and negative deviation of the grade. The results show that the relative error qualification rate of a single corresponding sample is 100%； the samples with grade positive deviation <0.07% account for 78.57% of the total number of samples，while those with grade negative deviation account for 21.43% of the total number of samples. The samples with grade positive deviation ≥0.07% account for samples 52.17% of the total，while those with negative deviation account for 47.83% of the total number of samples， indicating positive and negative deviations within the controllable range. The single project average grade relative error qualification rate is 100%. It shows that the split tube core barrel can be effectively applied to the exploration of weathered crust ion-adsorbed rare-earth minerals to realize resource evaluation.