Abstract: The Application of ICP-MS to Environmental AnalysisLi Jinying(China Institute of Atomic Energy, Beijing 102413,China)Abstract: A method of determination of REE and Th in sediment by ICP-MS has been developed. The influences of instrumental parameters and HNO_3,HCI and argon gas on REEand Th were studied. The difference of DL between ICP-MS and ICP-AES was discussed,and compared them with those in literature. The results of REE and Th in SDM-2/TM measured are good agree with the recommend values.Keywords: Environment, REE, Thorium, ICP-MS