Abstract: In order to elucidate the content and distribution characteristics of rare earth elements (REEs), as well as their sedimentary environment and source information, this study conducted a comprehensive analysis on particle size and REE tests using 53 surface sediment samples collected from Sandu’ao. Results revealed that the average REE content in the study area was 203.56 mg/kg, demonstrating an overall enrichment of the light REEs compared to heavy REEs. A moderate negative Eu anomaly was observed, while no apparent Ce anomaly was observed. Through the examination of sediment particle size parameters and Q-type cluster analysis, it was found that the sediment particle size composition of the study area was mainly silt, categorized into three types of sediment areas. The majority of these areas exhibited a relatively stable sedimentary environment, significantly influenced by sediment particle size and hydrodynamics. The analysis of standardized distribution curves, characteristic parameters, enrichment factor (EF), and discriminant function (DF) show that the study area is mainly land-based sources. Part of the substances may be traced back to the Yangtze River, with fine particulate matter being transported southward along the Zhejiang-Fujian coast due to the push of tides and waves, leading to water body exchange in the region. Tides and waves also abraded the surrounding bedrock, producing a substantial amount of clastic material. Additionally, a fraction of the materials may originate from rivers, streams, and gullies such as Huotong and Jiaoxi rivers, being deposited during the flood.