In this paper an introduction to Re Os isotopic system and its application to study of Cu Ni PGE deposit related to mafic ultramafic rock in the world is made. Re Os isotopic system, recently, is widely used in dating of precambrian bearing Cu Ni PGE mafic ultramafic rocks in terms of its high half life, explaining magmatic sources and evolution in combincation with other geochemical data. Moreover, Os, as one of 6 PGE, is frequently applied to the study of the origin of precious metals in magmatic Cu Ni PGE deposits. The author suggests that the Jinchuan, one of the largest magmatic Cu Ni sulfide deposits, may have occurred magma mixing during forming ore, and that the research of Re Os isotopic systematics to this ore deposit should be carred on in order to get further judgements.