Abstract: Rare earth elements (REEs) have been increasingly used to trace the material sources and the formation of rocks and minerals in various geochemical systems. However, in the detection of REEs in seawater samples, the high salinity and low concentration of REEs make the analysis quite challenging. The aim of this study is to effectively separate and enrich REEs from the background of high saline seawater and to quantitatively analyze REEs with ICP-MS. By the analyses of quantitation limit of REEs in seawater samples, the standard addition recovery experiments and the gradient standard addition recovery experiments, we evaluated the accuracy and enrichment efficiency of the method. By using different pH value in the process of co-precipitation and comparing sodium hydroxide and ammonia water as co-precipitators, we determined the influencing factors such as the dosage and types of co-precipitators in the process of enrichment. The feasibility of this method in practical samples is verified by comparing the results of REE partition curves with those of similar samples and the results of standard seawater detection. In summary, we have explored the experimental conditions of coprecipitation and enrichment for REEs in seawater samples, and this method can be applied to the actual detection of coastal seawater and pore seawater.