Hyriopsis cumingii and corresponding sediment in five respective monitoring sections of Poyang Lake were sampled in autumn 2014, followed by the detection of rare earth elements (REEs) in the soft tissue of Hyriopsis cumingii and sediments treated by BCR sequential exaction. As results, the mean value of total REEs in the soft tissue of Hyriopsis cumingii was 15.52 mg/kg, and light REEs were more easily accumulated, indicating that the biological effect of light REEs on Hyriopsis cumingii was stronger than heavy REEs. Correspondingly, the mean value of total REEs in sediments was 285.22 mg/kg with higher light REEs, suggesting the strong terrigenous properties. The REEs concentration in the sediment treated by BCR sequential extraction ranked as: residual fraction>reducible fraction>oxidizable fraction>exchangeable fraction. The exchangeable fraction displayed the lowest REEs concentration but the largest difference in spatial distribution; however, they were all under low risk level analyzed by Risk Assessment Code. Significant and positive correlations can be observed between REEs in Hyriopsis cumingii and that in the oxidizable fraction of sediments, suggesting that the bioavailability of REEs would mainly depend on REEs bound to organic matter.