Abstract: X-ray fluorescence spectroscopic technique(XRF) is used for studying the varieties and contents of trace elements of pearls in order to distingush the freshwater cultured pearls from saltwater cultured pearls.The optimizing working conditions of XRF for detecting the main and trace elements of pearls are also studied. The characteristic peaks of Mn and the values of Sr/Ca could be qualitatively analysed for distinguishing the varieties of pearls. With the working conditions of voltage being 30~35 kV,current being 0.50~0.80 mA and Pd Thick filter,element combination is Ca+Sr+Mn and the ratio of Sr/Ca is in a range from 0.14 to 0.37 for the freshwater cultured pearls; the element combination is mainly Ca and Sr,and the ratio of Sr/Ca is in a range from 0.46 to 0.71 for saltwater cultured pearls.Combined with element constituents and the ratio of Sr/Ca,saltwater cultured pearls could be nondestructively and quickly identified from the freshwater cultured pearls.