Abstract: A new method for the analysis of trace kalium, calcium, iron and silicon in high purity tungsten with reaction cell ICP-MS was studied. The four elements such as K, Ca, Fe and Si can all suffer the polyatomic ions interference and have the high background concentration in general ICP-MS determination. Thus, the four elements cannot be determined directly with ICP-MS, if the interferences were not eliminated. The new technology (reaction cell ICP-MS) can clear the interferences and decrease the background concentration obviously. The trace K, Ca, Fe and Si in high tungsten were analyzed with this new technology, and the satisfied results were obtained.