Abstract: In this research, instrumental neutron activation analysis (INAA) is used to analyzetwelve pure mineral samples selected from mantle xenoliths in Let-Qiong area (Leizhou Peninsula and Hainan ISland ). The spectrum gathering time of the analysing in INAA is 15000 seconds which are 5 to 10 times foranalysing granite. Leizhou and Hainan fluid-melt inclusions-free minerals have different REE contents, whichconfirmed the heterogeneity in Leizhou and Hainan mantle sources. The REE contents differences between sameminerals with and without fluid-melt inclusions selected from same mantle xenolith sample suggested that thefluid-melt inclusions are rich in REE, especially LREE. And the differences among the abundance of inclusionsand REE contents of same minerals selected from different mantle xenoliths and of different minerals selectedfrom same mantle xenolith, indicates the existence of heterogeneity in mantle fluids.