Abstract：In this paper, petrological and rare earth element analysis was carried out for limestone collected from the Jiudingshan Formation in northern Anhui Province, the origin of REE in limestone was studied, and the rare earth elements distribution patterns of the seawater were inversed. The results imply that rare earth elements in the limestone were mainly controlled by ancient oceans, without the influence of detrital material, that the total rare earth elements (REE) content is rather low, only 8.54?鄢10-6 on average, and the light and heavy REE are strictly fractionated, indicating normal neritic deposit. The REE distribution patterns of seawater is depleted in HREE, similar to things of limestone, and a very good positive correlation exists between Y/Ho and Y/Dy (R2=0.97) in limestone and seawater. The seawater has high Y/Ho ratios and negative Ce anomaly, with the δEuNASC being lower than 1, suggesting that the ancient seawater was similar to modern seawater.