Re is moderately incompatible element, while Os is highly compatible. As they are highly siderophile, Re-Os isotopic system can provide unique insight in dating and tracing research compared to other long-lived radiogenic isotope systems (e.g. Rb-Sr, Sm-Nd, U-Th-Pb ) which involve lithophile elements partitioning into silicate rather than metal or sulfide. The geologists have attached much importance to the particularity of Re-Os isotopic system and its application is getting popular. The author sums up and compares several kinds of sample digestion methods for Re-Os isotope analysis (NiS fire assay, Carius tube digestion, high pressure asher, leaching, and water disposing) , the procedures of separating Os ( conventional distillation, liquid Br2 and CCl4 or CHCl3 extraction, rapid extraction with low blank, minitype distillation) and purifying Os (microdistillation), improved mass spectrometry measurement of Os isotope(NTIMS, ICP-MS, in situ) and its application progress in the earth science research brought along the improved measuring method.